8.5 months pp but they were up to 90 day cycles initially. At 17 months pp they average 40 day cycles
Got my first one at 6 months or so, and my cycles used to be between 31-33days long but this cycle was more like 38 days.
I had one at 6 weeks then didn't have another until 9 months. Was regular after that.
I didn't have any periods until I was 14 months pp. They were regular after that though.