As soon as it comes out for Telltale's site, we'll let you know. It's out on Steam if you ordered it there.
EDIT: Telltale had a last minute internal server issue.
For those of you who can't wait to play TWD now, check your email. They have sent a STEAM key and you can download it from steam if you purchased it through Telltale's site. They should fix the server issue soon. If you still don't have your key, click here for instructions.
REMEMBER: I am a forum moderator, not staff. My job is to stop fights and get rid of spambots. I know just as much about the ETA on this as you; please don't email me about customer service issues. Thanks.