It is suggested to move BTC out of exchanges before Aug 1st to be sure if chain splits - to have both coins.
Also important: After Aug 1, be sure not to send coins anywhere that you don't control on both chains or which is sure to credit your coins on both chains (the latter refers to exchanges that implement auto-splitting), unless you have taken (somewhat complicated) measures to 'split' your coins into separate wallets.
Be careful even if it doesn't appear that the alternate chain is succeeding. The situation may evolve over some days (or longer)