If you're on the waitlist, that's about it for now. When you get to check-in at the terminal, you can see if anything's changed. If you're still on late, go to wherever they're handling dining changes as soon as you get on board and see if they can switch you.
And get to the port early so you'll have a good spot in line. If you board quickly, you can be one of the first in line. And check back after the first evening. There may be other people who want to change after that first dinner.