At what block does the PoS stage start?

POW/POS
4 Days of Mining - 96 HOUR POW

11.3 Million Coins
9% Stake

2 questions about the POS component...

1. Does POS only kick in after POW (block 2881)?
2. How long for coins to mature in wallet to generate stake?

Also you may want to update OP with Bittrex Thanks