C.S.
Hi Marcia,
I started having clock-work regular periods while exclusively breastfeeding my son. They started at 11 weeks post-partum and are still going. He's also still only brestfed (no solids) right now. He'll start on them in a couple more weeks.
My best friend has 4 children, with each one she didn't start having periods until she was weaning, and they had been on solids for awhile. They are also erratic for her... sometimes once a month, sometimes she skips a month.
Unfortunatly we're all so different you won't ever know by others experiences. What's nice to know is that it's all "normal" so you really don't have anything to worry about.