I'm scared of this end of sentence from bittrex comm : "Bittrex will make all reasonable attempts to credit our ZCL users BTCP but until we have a fully supported wallet, we can not guarantee tokens."
This means they cannot guarantee tokens, until fully supported BTCP wallet has been launched (in other words it means they cannot say the date). Official BTCP wallet is scheduled to be launched after fork and mainnet launch and the launch date will be published by BTCP dev team.