If you still need to buy BTC before the split and don't make it to Coinbase before they close up shop for the day, there's still hope:
Bitcoin offers a service called Simplex which lets you buy through BitStamp sort of. It works for US residents too!
I also highly recommend you send your funds directly to a cold-storage wallet. If you run a node especially, it works much faster. Only 10 minutes after I was verified I saw the transaction starting to go through confirmation.
So here's the rub: You need to have lots of very clear photos to send to them of your ID and even you holding your Credit Card. But it works. I can testify to it. This is directly through BitCoin.com and totally legit. It took them about 4 hours to get to me.
If you're buying a LOT of BTC, it will not be cheap though. There's a $40 fee if you buy $500 versus like $10 on CoinBase. Still, you're getting free BCC tomorrow anyway so is it worth it? You'll have to decide that for yourself.
If you found this useful send BTC or BCC my way please! 19WMSuqiw2g67L8sbNgWYFBZYvKYo8UMTL