Nobody likes a sneak attack from their period, even if they’ve had it for years.
In the olden days, women used to mark the start and end of their periods on paper calendars. Now, there are apps for that! If you decide to use an app, do some research to ensure the app does not collect or store your health data. Otherwise, a simple phone calendar or pen and paper will still do the trick!
If someone ever asks when your last period was, what they are really asking is: What was the first day of your last period? (Doctors will frequently ask this during health questionnaires, so it's good to know.) Your cycle begins on the first day of bleeding and ends the day before you begin your next period.
It’s also important to have a sense not just of when your period starts, but also how many days it continues and how heavy the bleeding is on each day. Most of the time, the heaviest days are at the beginning, and the bleeding gets progressively lighter until it stops. Apps do a great job of helping you track the start, the flow, and when to expect your next period.
But, periods can be unpredictable, especially when they first begin, and they even can remain irregular for months or years. To always be prepared, it’s helpful to keep a pad or tampon in the bottom of your bag or backpack just in case.