Wallet – Transferred Bitcoin before claiming Bitcoin cash

I had an offline wallet with a few bitcoins that I wanted to transfer to Coinbase today. Without thinking too much about it (lately did not know what's going on with Bitcoin), I transferred it to my own account and then read about Bitcoin Cash.

Did I mess up? Is it still possible to get Bitcoin cash from my transmitted bitcoins? Since it's an "old" wallet and the "same" bitcoin, would it work to send it back and then claim it?