All you need to have is a calendar to track your periods manually – a paper one or the one on your mobile or a computer.
Note the first day of your last menstrual period as day One.
Count the days in between before you start another period. Or you can just count 28 days.
Mark the last day that is when you are supposed to start your next period.
After a couple of months of marking likewise, you will be then able to figure out the actual menstrual cycle length, and you can calculate accordingly.
Another way is to keep track of the physical signs you experience in a period. Cramping, breast tenderness, white discharge are some of the common symptoms. The next time, when you start to experience such symptoms, you should be aware that your next period is going to start.
Emotional changes is another way to track your period manually. The fluctuating hormones alter your emotions such as feeling depressed, anxious or irritable for no apparent reason.