This varies with different types of BC some of them helps regulate your cycle which could make it easier but others stop your cycle completely so with those it could be anywhere from a month to two months before your cycle returns this completely through my cycles off I used a iUd and I think that is what actually caused me to not be able to conceive for 3 yrs it migrated and caused scarring... but yes I know ppl who've been on the depo shot missed it and got preggo right away...