Five days early menstruation is normal. In modern society, women are under great pressure in life, work and study, and occasionally five days early menstruation is a normal menstruation. Generally speaking, it is normal to have a period within seven days early or within seven days after the wrong period. If your period is frequently early for more than a week, you may have a decrease in ovarian function and need to have your sex hormones checked further. In general, the blood test for the sex hormone 6 test should be done from the second day of menstruation to the fourth day of menstruation. If the FSH and LH in the sex hormone panel increase, it indicates that the early menstruation is caused by the decrease of ovarian function.