Is it possible for me to start using aviane 21 anytime?

Aviane: "The patient is instructed to begin taking Aviane - 28 on the first Sunday after the onset of menstruation. If menstruation begins on a Sunday, the first tablet (orange) is taken that day. One orange tablet should be taken daily for 21 consecutive days, followed by one light-green inert tablet daily for 7 consecutive days." (http://www.drugs.com/dosage/aviane-28.html) Should be 21 active pills.