If I'm serving to a crowd, or at a party, I tend to do all of the prep ahead of time. Bake the chicken, dice the veggies, etc. and keep them covered in individual containers in the refrigerator until it's time to serve. Assembly is best done right before serving, so that the salad leaves don't wilt. I like to leave any bottles of dressing next to the salad, so each person can choose their flavor and quantity desired.