The best answer I can give is soonish. I know you would like more info, but thats the best I can do right now. We will announce it when the date is closer though, and you can preregister on the TW2 site and get emails of course.
I'm excited for this. While the retro feel of the current TW is nice, I'm sure the new version will be loads better, and its always lots of fun to be one of the first people to play a new game.
A date has been set for the opening of the Closed Beta of Tribal Wars 2! The launch will be on June 24th, 2014.
If you want more information, please go to this LINK
If you haven't preregistered yet, you can do it on www.tribalwars2.com and you might be selected to receive a Beta key!