Provera & PCOS

I recently found out I have PCOS. My periods are irregular. I either skip a month or only have spotting that month passing a few big clots. My cycles normally used to come the 24-26 like clock work until June when we started trying. To Where It’ll Come 24-26 or go into the next month & come on 10-12. I started taking Provera Wednesday October 2. I Started my period on yesterday. I took my last pill and about 10 minutes later my cycle was on. It’s heavier then normal & I have lots of cramping which I never get ... IS IT NORMAL TO START YOUR CYCLE THE SAME DAY YOU TOOK YOUR LAST PILL? Or Did My Body Have A Period On It’s Own?