It's in /etc/config/system
Under the "config system", it's the "timezone" option. Set it to one of these, and you should be good to go:
from: http://webcache.googleusercontent.com/search?q=cache:WvAyT4SoGvcJ:wiki.openwrt.org/doc/uci/system Time Zones Location TZ string Africa/Abidjan GMT0 Africa/Accra GMT0 Africa/Addis Ababa EAT-3 Africa/Algiers CET-1 Africa/Asmara EAT-3 Africa/Bamako GMT0 Africa/Bangui WAT-1 Africa/Banjul GMT0 Africa/Bissau GMT0 Africa/Blantyre CAT-2 Africa/Brazzaville WAT-1 Africa/Bujumbura CAT-2 Africa/Casablanca WET0 Africa/Ceuta CET-1CEST,M3.5.0,M10.5.0/3 Africa/Conakry GMT0 Africa/Dakar GMT0 Africa/Dar es Salaam EAT-3 Africa/Djibouti EAT-3 Africa/Douala WAT-1 Africa/El Aaiun WET0 Africa/Freetown GMT0 Africa/Gaborone CAT-2 Africa/Harare CAT-2 Africa/Johannesburg SAST-2 Africa/Kampala EAT-3 Africa/Khartoum EAT-3 Africa/Kigali CAT-2 Africa/Kinshasa WAT-1 Africa/Lagos WAT-1 Africa/Libreville WAT-1 Africa/Lome GMT0 Africa/Luanda WAT-1 Africa/Lubumbashi CAT-2 Africa/Lusaka CAT-2 Africa/Malabo WAT-1 Africa/Maputo CAT-2 Africa/Maseru SAST-2 Africa/Mbabane SAST-2 Africa/Mogadishu EAT-3 Africa/Monrovia GMT0 Africa/Nairobi EAT-3 Africa/Ndjamena WAT-1 Africa/Niamey WAT-1 Africa/Nouakchott GMT0 Africa/Ouagadougou GMT0 Africa/Porto-Novo WAT-1 Africa/Sao Tome GMT0 Africa/Tripoli EET-2 Africa/Tunis CET-1 Africa/Windhoek WAT-1WAST,M9.1.0,M4.1.0 America/Adak HAST10HADT,M3.2.0,M11.1.0 America/Anchorage AKST9AKDT,M3.2.0,M11.1.0 America/Anguilla AST4 America/Antigua AST4 America/Araguaina BRT3 America/Argentina/Buenos Aires ART3 America/Argentina/Catamarca ART3 America/Argentina/Cordoba ART3 America/Argentina/Jujuy ART3 America/Argentina/La Rioja ART3 America/Argentina/Mendoza ART3 America/Argentina/Rio Gallegos ART3 America/Argentina/Salta ART3 America/Argentina/San Juan ART3 America/Argentina/Tucuman ART3 America/Argentina/Ushuaia ART3 America/Aruba AST4 America/Asuncion PYT4PYST,M10.1.0/0,M4.2.0/0 America/Atikokan EST5 America/Bahia BRT3 America/Barbados AST4 America/Belem BRT3 America/Belize CST6 America/Blanc-Sablon AST4 America/Boa Vista AMT4 America/Bogota COT5 America/Boise MST7MDT,M3.2.0,M11.1.0 America/Cambridge Bay MST7MDT,M3.2.0,M11.1.0 America/Campo Grande AMT4AMST,M10.3.0/0,M2.3.0/0 America/Cancun CST6CDT,M4.1.0,M10.5.0 America/Caracas VET4:30 America/Cayenne GFT3 America/Cayman EST5 America/Chicago CST6CDT,M3.2.0,M11.1.0 America/Chihuahua MST7MDT,M4.1.0,M10.5.0 America/Costa Rica CST6 America/Cuiaba AMT4AMST,M10.3.0/0,M2.3.0/0 America/Curacao AST4 America/Danmarkshavn GMT0 America/Dawson PST8PDT,M3.2.0,M11.1.0 America/Dawson Creek MST7 America/Denver MST7MDT,M3.2.0,M11.1.0 America/Detroit EST5EDT,M3.2.0,M11.1.0 America/Dominica AST4 America/Edmonton MST7MDT,M3.2.0,M11.1.0 America/Eirunepe AMT4 America/El Salvador CST6 America/Fortaleza BRT3 America/Glace Bay AST4ADT,M3.2.0,M11.1.0 America/Goose Bay AST4ADT,M3.2.0/0:01,M11.1.0/0:01 America/Grand Turk EST5EDT,M3.2.0,M11.1.0 America/Grenada AST4 America/Guadeloupe AST4 America/Guatemala CST6 America/Guayaquil ECT5 America/Guyana GYT4 America/Halifax AST4ADT,M3.2.0,M11.1.0 America/Havana CST5CDT,M3.2.0/0,M10.5.0/1 America/Hermosillo MST7 America/Indiana/Indianapolis EST5EDT,M3.2.0,M11.1.0 America/Indiana/Knox CST6CDT,M3.2.0,M11.1.0 America/Indiana/Marengo EST5EDT,M3.2.0,M11.1.0 America/Indiana/Petersburg EST5EDT,M3.2.0,M11.1.0 America/Indiana/Tell City CST6CDT,M3.2.0,M11.1.0 America/Indiana/Vevay EST5EDT,M3.2.0,M11.1.0 America/Indiana/Vincennes EST5EDT,M3.2.0,M11.1.0 America/Indiana/Winamac EST5EDT,M3.2.0,M11.1.0 America/Inuvik MST7MDT,M3.2.0,M11.1.0 America/Iqaluit EST5EDT,M3.2.0,M11.1.0 America/Jamaica EST5 America/Juneau AKST9AKDT,M3.2.0,M11.1.0 America/Kentucky/Louisville EST5EDT,M3.2.0,M11.1.0 America/Kentucky/Monticello EST5EDT,M3.2.0,M11.1.0 America/La Paz BOT4 America/Lima PET5 America/Los Angeles PST8PDT,M3.2.0,M11.1.0 America/Maceio BRT3 America/Managua CST6 America/Manaus AMT4 America/Marigot AST4 America/Martinique AST4 America/Matamoros CST6CDT,M3.2.0,M11.1.0 America/Mazatlan MST7MDT,M4.1.0,M10.5.0 America/Menominee CST6CDT,M3.2.0,M11.1.0 America/Merida CST6CDT,M4.1.0,M10.5.0 America/Mexico City CST6CDT,M4.1.0,M10.5.0 America/Miquelon PMST3PMDT,M3.2.0,M11.1.0 America/Moncton AST4ADT,M3.2.0,M11.1.0 America/Monterrey CST6CDT,M4.1.0,M10.5.0 America/Montevideo UYT3UYST,M10.1.0,M3.2.0 America/Montreal EST5EDT,M3.2.0,M11.1.0 America/Montserrat AST4 America/Nassau EST5EDT,M3.2.0,M11.1.0 America/New York EST5EDT,M3.2.0,M11.1.0 America/Nipigon EST5EDT,M3.2.0,M11.1.0 America/Nome AKST9AKDT,M3.2.0,M11.1.0 America/Noronha FNT2 America/North Dakota/Center CST6CDT,M3.2.0,M11.1.0 America/North Dakota/New Salem CST6CDT,M3.2.0,M11.1.0 America/Ojinaga MST7MDT,M3.2.0,M11.1.0 America/Panama EST5 America/Pangnirtung EST5EDT,M3.2.0,M11.1.0 America/Paramaribo SRT3 America/Phoenix MST7 America/Port of Spain AST4 America/Port-au-Prince EST5 America/Porto Velho AMT4 America/Puerto Rico AST4 America/Rainy River CST6CDT,M3.2.0,M11.1.0 America/Rankin Inlet CST6CDT,M3.2.0,M11.1.0 America/Recife BRT3 America/Regina CST6 America/Rio Branco AMT4 America/Santa Isabel PST8PDT,M4.1.0,M10.5.0 America/Santarem BRT3 America/Santo Domingo AST4 America/Sao Paulo BRT3BRST,M10.3.0/0,M2.3.0/0 America/Scoresbysund EGT1EGST,M3.5.0/0,M10.5.0/1 America/Shiprock MST7MDT,M3.2.0,M11.1.0 America/St Barthelemy AST4 America/St Johns NST3:30NDT,M3.2.0/0:01,M11.1.0/0:01 America/St Kitts AST4 America/St Lucia AST4 America/St Thomas AST4 America/St Vincent AST4 America/Swift Current CST6 America/Tegucigalpa CST6 America/Thule AST4ADT,M3.2.0,M11.1.0 America/Thunder Bay EST5EDT,M3.2.0,M11.1.0 America/Tijuana PST8PDT,M3.2.0,M11.1.0 America/Toronto EST5EDT,M3.2.0,M11.1.0 America/Tortola AST4 America/Vancouver PST8PDT,M3.2.0,M11.1.0 America/Whitehorse PST8PDT,M3.2.0,M11.1.0 America/Winnipeg CST6CDT,M3.2.0,M11.1.0 America/Yakutat AKST9AKDT,M3.2.0,M11.1.0 America/Yellowknife MST7MDT,M3.2.0,M11.1.0 Antarctica/Casey WST-8 Antarctica/Davis DAVT-7 Antarctica/DumontDUrville DDUT-10 Antarctica/Macquarie MIST-11 Antarctica/Mawson MAWT-5 Antarctica/McMurdo NZST-12NZDT,M9.5.0,M4.1.0/3 Antarctica/Rothera ROTT3 Antarctica/South Pole NZST-12NZDT,M9.5.0,M4.1.0/3 Antarctica/Syowa SYOT-3 Antarctica/Vostok VOST-6 Arctic/Longyearbyen CET-1CEST,M3.5.0,M10.5.0/3 Asia/Aden AST-3 Asia/Almaty ALMT-6 Asia/Anadyr ANAT-11ANAST,M3.5.0,M10.5.0/3 Asia/Aqtau AQTT-5 Asia/Aqtobe AQTT-5 Asia/Ashgabat TMT-5 Asia/Baghdad AST-3 Asia/Bahrain AST-3 Asia/Baku AZT-4AZST,M3.5.0/4,M10.5.0/5 Asia/Bangkok ICT-7 Asia/Beirut EET-2EEST,M3.5.0/0,M10.5.0/0 Asia/Bishkek KGT-6 Asia/Brunei BNT-8 Asia/Choibalsan CHOT-8 Asia/Chongqing CST-8 Asia/Colombo IST-5:30 Asia/Damascus EET-2EEST,M4.1.5/0,M10.5.5/0 Asia/Dhaka BDT-6 Asia/Dili TLT-9 Asia/Dubai GST-4 Asia/Dushanbe TJT-5 Asia/Gaza EET-2EEST,M3.5.6/0:01,M9.1.5 Asia/Harbin CST-8 Asia/Ho Chi Minh ICT-7 Asia/Hong Kong HKT-8 Asia/Hovd HOVT-7 Asia/Irkutsk IRKT-8IRKST,M3.5.0,M10.5.0/3 Asia/Jakarta WIT-7 Asia/Jayapura EIT-9 Asia/Kabul AFT-4:30 Asia/Kamchatka PETT-11PETST,M3.5.0,M10.5.0/3 Asia/Karachi PKT-5 Asia/Kashgar CST-8 Asia/Kathmandu NPT-5:45 Asia/Kolkata IST-5:30 Asia/Krasnoyarsk KRAT-7KRAST,M3.5.0,M10.5.0/3 Asia/Kuala Lumpur MYT-8 Asia/Kuching MYT-8 Asia/Kuwait AST-3 Asia/Macau CST-8 Asia/Magadan MAGT-11MAGST,M3.5.0,M10.5.0/3 Asia/Makassar CIT-8 Asia/Manila PHT-8 Asia/Muscat GST-4 Asia/Nicosia EET-2EEST,M3.5.0/3,M10.5.0/4 Asia/Novokuznetsk NOVT-6NOVST,M3.5.0,M10.5.0/3 Asia/Novosibirsk NOVT-6NOVST,M3.5.0,M10.5.0/3 Asia/Omsk OMST-7 Asia/Oral ORAT-5 Asia/Phnom Penh ICT-7 Asia/Pontianak WIT-7 Asia/Pyongyang KST-9 Asia/Qatar AST-3 Asia/Qyzylorda QYZT-6 Asia/Rangoon MMT-6:30 Asia/Riyadh AST-3 Asia/Sakhalin SAKT-10SAKST,M3.5.0,M10.5.0/3 Asia/Samarkand UZT-5 Asia/Seoul KST-9 Asia/Shanghai CST-8 Asia/Singapore SGT-8 Asia/Taipei CST-8 Asia/Tashkent UZT-5 Asia/Tbilisi GET-4 Asia/Thimphu BTT-6 Asia/Tokyo JST-9 Asia/Ulaanbaatar ULAT-8 Asia/Urumqi CST-8 Asia/Vientiane ICT-7 Asia/Vladivostok VLAT-10VLAST,M3.5.0,M10.5.0/3 Asia/Yakutsk YAKT-9YAKST,M3.5.0,M10.5.0/3 Asia/Yekaterinburg YEKT-5YEKST,M3.5.0,M10.5.0/3 Asia/Yerevan AMT-4AMST,M3.5.0,M10.5.0/3 Atlantic/Azores AZOT1AZOST,M3.5.0/0,M10.5.0/1 Atlantic/Bermuda AST4ADT,M3.2.0,M11.1.0 Atlantic/Canary WET0WEST,M3.5.0/1,M10.5.0 Atlantic/Cape Verde CVT1 Atlantic/Faroe WET0WEST,M3.5.0/1,M10.5.0 Atlantic/Madeira WET0WEST,M3.5.0/1,M10.5.0 Atlantic/Reykjavik GMT0 Atlantic/South Georgia GST2 Atlantic/St Helena GMT0 Atlantic/Stanley FKT4FKST,M9.1.0,M4.3.0 Australia/Adelaide CST-9:30CST,M10.1.0,M4.1.0/3 Australia/Brisbane EST-10 Australia/Broken Hill CST-9:30CST,M10.1.0,M4.1.0/3 Australia/Currie EST-10EST,M10.1.0,M4.1.0/3 Australia/Darwin CST-9:30 Australia/Eucla CWST-8:45 Australia/Hobart EST-10EST,M10.1.0,M4.1.0/3 Australia/Lindeman EST-10 Australia/Lord Howe LHST-10:30LHST-11,M10.1.0,M4.1.0 Australia/Melbourne EST-10EST,M10.1.0,M4.1.0/3 Australia/Perth WST-8 Australia/Sydney EST-10EST,M10.1.0,M4.1.0/3 Europe/Amsterdam CET-1CEST,M3.5.0,M10.5.0/3 Europe/Andorra CET-1CEST,M3.5.0,M10.5.0/3 Europe/Athens EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Belgrade CET-1CEST,M3.5.0,M10.5.0/3 Europe/Berlin CET-1CEST,M3.5.0,M10.5.0/3 Europe/Bratislava CET-1CEST,M3.5.0,M10.5.0/3 Europe/Brussels CET-1CEST,M3.5.0,M10.5.0/3 Europe/Bucharest EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Budapest CET-1CEST,M3.5.0,M10.5.0/3 Europe/Chisinau EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Copenhagen CET-1CEST,M3.5.0,M10.5.0/3 Europe/Dublin GMT0IST,M3.5.0/1,M10.5.0 Europe/Gibraltar CET-1CEST,M3.5.0,M10.5.0/3 Europe/Guernsey GMT0BST,M3.5.0/1,M10.5.0 Europe/Helsinki EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Isle of Man GMT0BST,M3.5.0/1,M10.5.0 Europe/Istanbul EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Jersey GMT0BST,M3.5.0/1,M10.5.0 Europe/Kaliningrad EET-2EEST,M3.5.0,M10.5.0/3 Europe/Kiev EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Lisbon WET0WEST,M3.5.0/1,M10.5.0 Europe/Ljubljana CET-1CEST,M3.5.0,M10.5.0/3 Europe/London GMT0BST,M3.5.0/1,M10.5.0 Europe/Luxembourg CET-1CEST,M3.5.0,M10.5.0/3 Europe/Madrid CET-1CEST,M3.5.0,M10.5.0/3 Europe/Malta CET-1CEST,M3.5.0,M10.5.0/3 Europe/Mariehamn EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Minsk EET-2EEST,M3.5.0,M10.5.0/3 Europe/Monaco CET-1CEST,M3.5.0,M10.5.0/3 Europe/Moscow MSK-4 Europe/Oslo CET-1CEST,M3.5.0,M10.5.0/3 Europe/Paris CET-1CEST,M3.5.0,M10.5.0/3 Europe/Podgorica CET-1CEST,M3.5.0,M10.5.0/3 Europe/Prague CET-1CEST,M3.5.0,M10.5.0/3 Europe/Riga EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Rome CET-1CEST,M3.5.0,M10.5.0/3 Europe/Samara SAMT-3SAMST,M3.5.0,M10.5.0/3 Europe/San Marino CET-1CEST,M3.5.0,M10.5.0/3 Europe/Sarajevo CET-1CEST,M3.5.0,M10.5.0/3 Europe/Simferopol EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Skopje CET-1CEST,M3.5.0,M10.5.0/3 Europe/Sofia EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Stockholm CET-1CEST,M3.5.0,M10.5.0/3 Europe/Tallinn EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Tirane CET-1CEST,M3.5.0,M10.5.0/3 Europe/Uzhgorod EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Vaduz CET-1CEST,M3.5.0,M10.5.0/3 Europe/Vatican CET-1CEST,M3.5.0,M10.5.0/3 Europe/Vienna CET-1CEST,M3.5.0,M10.5.0/3 Europe/Vilnius EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Volgograd VOLT-3VOLST,M3.5.0,M10.5.0/3 Europe/Warsaw CET-1CEST,M3.5.0,M10.5.0/3 Europe/Zagreb CET-1CEST,M3.5.0,M10.5.0/3 Europe/Zaporozhye EET-2EEST,M3.5.0/3,M10.5.0/4 Europe/Zurich CET-1CEST,M3.5.0,M10.5.0/3 Indian/Antananarivo EAT-3 Indian/Chagos IOT-6 Indian/Christmas CXT-7 Indian/Cocos CCT-6:30 Indian/Comoro EAT-3 Indian/Kerguelen TFT-5 Indian/Mahe SCT-4 Indian/Maldives MVT-5 Indian/Mauritius MUT-4 Indian/Mayotte EAT-3 Indian/Reunion RET-4 Pacific/Apia WST11 Pacific/Auckland NZST-12NZDT,M9.5.0,M4.1.0/3 Pacific/Chatham CHAST-12:45CHADT,M9.5.0/2:45,M4.1.0/3:45 Pacific/Efate VUT-11 Pacific/Enderbury PHOT-13 Pacific/Fakaofo TKT10 Pacific/Fiji FJT-12 Pacific/Funafuti TVT-12 Pacific/Galapagos GALT6 Pacific/Gambier GAMT9 Pacific/Guadalcanal SBT-11 Pacific/Guam ChST-10 Pacific/Honolulu HST10 Pacific/Johnston HST10 Pacific/Kiritimati LINT-14 Pacific/Kosrae KOST-11 Pacific/Kwajalein MHT-12 Pacific/Majuro MHT-12 Pacific/Marquesas MART9:30 Pacific/Midway SST11 Pacific/Nauru NRT-12 Pacific/Niue NUT11 Pacific/Norfolk NFT-11:30 Pacific/Noumea NCT-11 Pacific/Pago Pago SST11 Pacific/Palau PWT-9 Pacific/Pitcairn PST8 Pacific/Ponape PONT-11 Pacific/Port Moresby PGT-10 Pacific/Rarotonga CKT10 Pacific/Saipan ChST-10 Pacific/Tahiti TAHT10 Pacific/Tarawa GILT-12 Pacific/Tongatapu TOT-13 Pacific/Truk TRUT-10 Pacific/Wake WAKT-12 Pacific/Wallis WFT-12
