We don't tend to announce patch release dates until very shortly before as there could be any number of issues that would prevent the patch from going live even days before it's scheduled to. There is always a chance it could be delayed, even if it's very low. For that reason we tend to not announce patch release dates. But, there have been quite a few hints.
2/12/13 - http://us.battle.net/wow/en/forum/topic/7909111142 If you’ve already made plans and sunk your Valor, don’t fret! As of this announcement, and even if you have 0 Valor currently, you still have enough time to cap out at 3000 Valor before patch 5.2 goes live. (It’s math!)