I'm not quite sure what you're asking, but it sounds like you're wondering at what age it would be appropriate for a girl to start taking measures to regulate an irregular cycle. I know many women who have irregular periods and take birth control to keep them regular, and all of them started around age 16 and 17. That doesn't mean this is THE age it should be done...that is entirely up to you and your family.
Some women experience particularly excessive/intense symptoms with menstruation (heavy flow, very painful cramps, irregularity) If your daughter is thinking about birth control or other methods that can make menstruation easier, make an appointment for her with a gynecologist and he/she will discuss what can be done. There are tons of options when it comes to this, she's certain to find one that will work for her, or she may decide she doesn't need anything after all.
I hope that's close to what you were looking for! Good luck!
More variation than that may indicate to us the beginning of Peri menopause or hormonal events that controls menstruation. A wide variety of factors can be responsible for irregular periods, among them: Overexercise, Breastfeeding, Hormonal imbalances related to Peri menopause, Eating disorders etc. Strictly speaking, women aren’t considered menopausal until they have gone for one year without a menstrual period. They are generally an indication of hormonal imbalance to overcome it use http://www.cupissima.com , not necessarily related to menopause.