Most girls and women start their period around the start of puberty. This can happen as early as 9: this is called early onset menstruation and is not normal. Usually only present when a hormonal disorder is in effect. It can occur as late as 17 too in some women, the amount of body fat can effect how regularity and how much a woman has her period. In short, it happens different for everyone, just like the effects of male puberty.
