What are the signs of a first period. There is usually a little blood on your underwear before you get your period. A woman’s body undergoes a series of changes before her first period. Measure height and weight, twice every six months after a girl reaches puberty at age 11-14. If several measurements reveal a sudden increase in height and weight, this is a sign that menstruation may occur in the following six months. Breast development. If the breasts are found to be developing, expanding, with an areola and a hard knot when touched, the first menstruation will occur within the next two years. Look for leucorrhoea, if it comes out of the girl’s vagina, a clear, colorless, odorless and slightly sticky fluid like an egg, it signals that the first menstruation is coming in 2-3 days. If there are pimples on the face, cheeks and forehead with small pustules, it is a sign that menstruation will come in 2-3 months.