It really depends person to person (even baby to baby) but if you ask females within your family it might give you some ideas.

With my first it returned around 6 months (exclusively breastfeeding, not sleeping through by a long shot, hadn't began solids) and was regular from that point forward.

With my second it returned at 6 WEEKS and has been regular ever since. At the time I was breastfeeding both my girls!!!