text: confused...? ok i should know this but i don't. when you are tryin to igure out your menstral cycle length do you go from the day you start one period to the day you start the next or from the last day of one period to the first day of the next, or what? the day you start your period....28 days after is when you should start your next period.  some women can vary from 28 to 30+ days. but still, count 28 days on the calander anyway until you get your pattern figured out.