It takes a while to attach your bank account to Coinbase. If you use the Bank wire transfer method, it might take a week at least. I remembered during sign up they asked for my bank account's username and password for fast authentication, which really bothered me and triggered red flags. I choose the slower bank wire method because I don't want to give them full access to my bank account.
RE: How do I get my first Bitcoin? Coinbase vs BitPay vs GoCoin