Everyone is different, but in my experience it took a few months for my period to get "regular" once it came back. Initially, I had several cycles that were all over the place, anywhere from 25 to almost 50 days, and I was always quite regular before. One of my sisters reccomended taking a flax oil supplement to help my cycles and I did. I don't know if it was coincidence or not, but as soon as I started taking it I went right back to my 26-28 day cycles. I probably went 5 or so months with irregular cycles, but once they went back to regular, they stayed that way. Hope that helps.
Happy wife of T mom to L and M