Newest update from Bittrex says that the snapshot of the blockchain (i.e. the "public fork") is estimated to happen at around 10 am UTC on October 24th. BTG will be available for trading after November 1st, most likely, but on which exchanges is yet uncertain. However, they say that the replay protection isn't implemented on BTG.

I don't know... It's a mess. Here is the announcement if you want to take a look.