Girls can start their periods (also referred to as menstruation) any time between 8 and 18 years old, but most girls start their menstrual cycle between the ages of 12 and 13. You might have mixed emotions about getting your period. Some girls can’t wait to start their periods and feel left out if they haven’t got theirs, especially if all their girlfriends have. Whereas other girls would be perfectly happy to be get theirs at an older age. There is no way to make your period come sooner or delay it from happening. Don’t panic if you haven’t started your period yet – it will happen when your body is ready.