Is ghusl required merely upon the drying of the cloth or the presence of transparent vaginal moisture, without concern for any subsequent turbid or yellowish discharge, or is it necessary to wait for a specific period?

It appears the questioner is afflicted with waswas (obsessive doubts) regarding purity. The brownish and yellowish discharges connected to menstruation are considered menstrual blood as long as they do not exceed 15 days. Wudu' (ablution) does not suffice for ghusl (ritual bath) after the end of menstruation. The signs of menstruation ending are the cessation of blood and what is considered equivalent to it, or the appearance of the white discharge (al-qassah al-bayda'). She should have continued to consider herself menstruating until the yellowish or brownish discharge ceased. There is no need for excessive examination; it suffices to test the area with a cloth. If it comes out clean, she has become pure and must perform ghusl and pray. If brownish discharge or blood appears after menstruation has ceased, and this occurs within her usual period days, then it is menstruation; otherwise, it is not. Vaginal discharge after purity is not considered menstruation.