I have done that many times--I don't add any vinegar, just make sure they are totally covered with water--any potato that sticks out into the air will brown. Which won't hurt you--I read that browned potatoes are a higher source of vitamin C. As long as they are not all brown, they won't change the color of your mash, either.
Uncle Bob, I have done it for big family dinners--any thing I can do the day before is a good thing.
I just haven't been the same
since that house fell on my sister.