When I first started smoking I followed the advice to prep/rub the night before, wrap in plastic, store in the refrigerator, then pull out and let warm close to room temp before putting on the smoker. I stopped all that.
Except for brines and marinades which I still target for 18-24 hours, I have stopped putting rubs on my meats the night before because IMO they diminished the natural flavor of the meat and emphasized the flavor of the rub. Now, whether I'm smoking ribs, butts, briskets, loins, chuckies, chickens, etc, I apply the whatever rub I'm using just before they go on the smoker. I leave the meat in the frig until the smoker is ready, then I pull it out, prep and lightly rub it, then on the smoker it goes as cold as it can be without being frozen. It absorbs more smoke while climbing from a low temp plus I'm using a lot less rub these days. I am enjoying the final results more. I want to taste meat, smoke, then rub in that order. Once again, IMO brines, marinades, and rubs should complement the meat, not the other way around, but each person has their own preferences.
Also, I'm smoking choice grade meat that definitely has flavor. I have tasted choice grade meats that are practically tasteless from one major outlet in my area. In that case yeah, the brine, marinade, and rub IS the flavor.