You can import your PTS wallet any time. The blockchain is not going to be reset. In fact you'd be wise to do so for a couple of reasons:
1) It will allow you to move your stake off the genesis block. This prevents theft in the event your PTS wallet is compromised.
2) You can vote! It's worth checking out the delegate sub forum. A good vote right off the bat would be dev0.nikolai (toast)
. He's currently in 105th position and needs all the help he can get to get into a paid position. He's a primary developer on BTS.
As for when the new client is coming out...not sure. Word on the street is end of November but I wouldn't be surprised if it gets pushed back a bit.