Back on July 27, 2017, it took about 3 hrs for the transaction to appear on the Bitcoin blockchain. So you just have to be patient. If it doesn't show up after 6+ hrs, then I'd be concerned.
Hopefully, Segwit helps to alleviate this type of network congestion. And then the 2 MB block increase in Nov should improve the transaction flow even more.
RE: Coinbase Delays BTC Withdrawals, Multibit HD Dies, BTC-E Ethereum Funds Move