It has already BEGUN!
Bittrex has put their bitcoin wallet into maintenance RIGHT NOW!
BTC is not allowed to be transfered to and from ALL their customers wallets , starting less than an hour ago.
https://steemit.com/trending/@medevlo/looks-like-bittrex-has-shut-off-any-withdrawals-and-deposits-to-their-wallets-it-has-begun
So those who wanted BCC at the last minute from them.
You are to late unfortunately.