Those lettuces are pretty crisp/sturdy, I would go ahead with it today. Wash and dry it in a salad spinner if you have one.

OP here- thanks to all. It is radicchio, romaine, and endive. Yes, all need to be washed. I was hoping for something else I could get done today, but it seems the consensus is to wait until tomorrow. Thanks so much!

Just keep them separate and don't chop the lettuce.

Cut the veggies up, keep the different veggies in separate containers.
The trick my mom taught me for the lettuce was to get a paper towel, get it wet, wring out the excess water, and place it on top of the lettuce. Gives it moisture and helps it stay crisp. She did this part on day-off for the lettuce. For day before, I agree with PP that the way to go is air tight container with lid.

Should be fine unless you are washing the lettuce. That will wilt. Also, i tend to find that tomatoes get a little mushy when cut the night before. But I also prefer really firm tomatoes, so that might just be a matter of taste.

An air tight container with a lid vs a bowl with saran wrap seems to help keep it crisp.

I'm really embarrassed to even ask this- is it OK to chop all the lettuce and veggies a day ahead, as long as you don't dress the salad yet? They won't start wilting, will they?