Cat has abscess this morning....will he be okay until tomorrow?

Just keep the wound clean until you can get the cat in. Should be fine until tomorrow. My cat has had a couple that healed on their own after applying a warm compress and keeping the wound cleaned out, and the cat inside where it couldn't get into anything. I would definitely check with the vet to see if it needs drained.

I'm not a vet, so i can't say yes or no. But you can do warm compresses with warm water and a wash cloth a few times. This will help encourage it to drain if it isn't already. He definitely needs to have it cleaned out and start on antibiotics ASAP though. The emergency vet services at All Valley or WestVet are both excellent and pretty reasonably priced.