can i wash and trim brussels sprouts tonight for thanksgiving?

I buy stalks of brussels sprouts at our farmers market the Saturday before Thanksgiving and trim them that day.

Yes of course. Just refrigerate them, covered.

May I respectfully suggest that you store them in cold water to which you've added a couple generous pinches of salt? I've been doing this for years, after seeing this tip in one of the earliest editions of "The Joy of Cooking" (1940's). The brine allows the Brussels sprouts to retain their bright color when cooked, and they seem much fresher (less dry, of course) than when you prep and pop them in a bag. Also, I never blanch Brussels sprouts, though some recipes recommend that you do. I find that it guarantees that the outer leaves will be mushy, which I simply cannot abide. ;o)

Yes, who wants to do it in the morning! once less prep to worry about.

Absolutely. Clean, cut and store in an air tight container and refrigerated.