J.R., Aboslutely with Henry on this one, 100%. Save yourself a ton of trouble by purchasing a prehung unit.
Often, interior rough openings called for are as much as 3" larger than the actual door; a 32" door will ask for a 35" opening. Personally I find no reason for this much overage IF you are paying attention to keeping your framing level; a 34" r.o. is plenty in such case.