Let's see...
August 2013 - 2.0
November 2013 - 2.1 (11.14.13 - Lightning FATE)
February 2014 - PS4 beta (2.22.14), potential 2.2?
May 2014 - potential 2.3? (DX11 client?)

So it will either be Valentine's Day or May Day (Beltane)...