Board Thread:Admin Support/@comment-170.211.118.24-20160224190606/@comment-1173941-20160225003328

Looking at the history for the page Sword Art Online Wiki, You'll see that the first edit on the wiki was on December 3, 2011, which is around the time that the anime was announced. Though, serious activity didn't really start until the coming months.

Though, I'm not sure if the first edit could count as a "date of publication", especially on a website that is constantly updating information, like a wiki.