Is it normal to have period three days before it's due and the blood is dark brown ....

Early menses: Menstrual cycles are not always regular for a number of reasons including pregnancy, anovulatory cycle, hormone imbalance, missing a birth control pill, miscarriage, or infection. Dark brown blood occurs when the flow is slow and the blood has time to be oxidized in the vagina. I would check to make sure you are not pregnant. If your next period is irregular I would seek medical attention.