Aside from the heavy usage of iPhone 4's used within 1x02, which ran from 2011-2013, reddit user archerthegreat had posted this screencap following the episode. What do you think, ONTD? Does it follow the user-speculated timeline of the internet? Will Robert Kirkman debunk this? Further speculation within the thread suggests that the Walking Dead, now in its 6th season, is currently in early 2012.
The date on the banner states 08/07/10. Or, for those of you who don't use the proper dating system ('MURICA!!!!!), the date is August 7th, 2010 -- pointing us to at least the year 2010. Month debatable as school just started in California.