When I was on the NuvaRing, it actually shortened my periods to a couple to three days at the most and it was never an actual "flow" it was more of a spotting. Everyone is different so you may not get your period at all on it. Just keep track and make sure you put in your new one when supposed to :)
Well before this I had the shot and I never had a period on that. So maybe its way off balance
My first few months on the ring, it took about 2-3 days after I took it out before I started. Everyone's body ajusts to the ring different but if you don't start by the time it's time to put in a new ring, I would at least call a doc