Is it an official info? 6 weeks sounds pretty nice.
Im Guesstimating.
Alan Wilson said in the next few weeks they will slowly be re-vealing some stuff and slowly ramping up from there:
http://youtu.be/kiZ20bYoN_8?t=7m26s
If they are revealing a few things in the next couple of weeks, and at the start of the interview he said it would be on Early Access on steam.
Id say i might be correct? but it could be 8 weeks. It might coincide with the summer sales.
Or, they might do the Summer event on KF1 and then when that ends release KF2 Early Access. Maybe end of July? Early August?
Im thinking after summer sales, KF1 will be discounted heavily, with new event combined with summer sale, in game advertising in KF 1, and then a release of KF2 once they have built up some serious interest.