J.G.
I have been on Micronor or the generic equivalent many times, and each time it was also our contraception option as well as hormone treatment. I never got pregnant while taking it, but did take it every night before bedtime consistently without missing a day. I did have breakthrough bleeding while on it, but that seems to be a pretty common thing. I'm on it again now for contraception 3 months postpartum after our first child.
It is supposed to work like any other birth control - if you start it immediately following another type of pill regimen you should be fine. Otherwise, my doctor always recommended taking one full cycle of the micronor before dropping the backup contraception.
Good luck!