So can I still transfer all my altcoins on bittrex to btc and Receiver bcc for it?
I don't know if you can transfer funds now or not. They started locking down transactions 24hrs prior to the split tonight. And it sounds like they will remain that way until they are confident the network is stable. So it will be a wait and see from here.
I don't know I would risk trying to move your funds now.
If you are desperate for BCC and are too late to transfer BTC out of your exchange you can switch to any exchange that __promised__ (risk implied) to provide any coins there is a split. Eg. assume you are on Gdax, you can't move your BTC out. If you buy BTC, it only gets BTC. You can trade of ETH (or LTC) and transfer to an exchange that will credit on fork moment, like Bittrex. Transfer the ETH or LTC to Bittrex, then buy BTC and HOLD until after the snapshop 5:20 Pacific Time (don't sell so close to the snapshot though!).
Challenge is you don't know when the BCC wallet will be made available for transfers, nor when and if they will open BCC for trading (there). But it's best than having BTC at Coinbase or Poloniex. You have also missed the windows for those that did Token splits (like Bitfinex).