Most of your BSN classes probably aren't going to be "nursing" classes -- you'll be taking things like statistics, nursing research, ethics, nursing informatics, service learning, organizational systems, leadership, communication. Think about it -- the 18yo kids who go into a BSN program right out of high school don't have any nursing experience before they take those classes, so I don't think that having nursing experience under your belt will make much of a difference in your ability to competently pass those classes.
However, whether to take time off or not depends on your personal need to recharge, or whether you'd like to offer yourself some time to acclimate to your new nursing job before taking on more stress.
I personally will probably take 6-12 months off before starting an online RN-to-BSN program. Between pre-reqs and nursing school, I've been at this for four years while also working a full-time office job and being a hockey mom. I'd like to spend a little time with my kid and maybe take the time to get a massage or go on a real vacation (sorry, weekends at a hockey tournament do NOT count as vacations!) before jumping back into the fray of homework and exams. But some of my classmates prefer to just keep right on going without stopping. Just a personal preference thing.