Is it necessary for the woman experiencing irregular bleeding (mustahadah) to establish a regular cycle in order to apply the rulings of irregular bleeding from the beginning of each month?

Istihada (prolonged vaginal bleeding outside of menstruation) is not determined by a woman's usual menstrual cycle. Rather, its ruling is established if the blood flow exceeds fifteen days. If a woman has a regular cycle, she observes her usual period, then performs ghusl (ritual purification), and performs wudu (ablution) for each prayer after its time has begun, taking precautions (to prevent leakage). If she does not have a regular cycle but can distinguish (between menstrual and istihada blood), she acts according to her discernment: she considers what has the characteristics of menstruation to be menses and performs ghusl thereafter, and anything else is istihada. If she is neither accustomed (to a regular cycle) nor able to distinguish, she observes the predominant menstrual habit of women (six or seven days), then performs ghusl, and any excess (bleeding) is istihada.