If you usually have regular periods and your menstrual cycle is around 28-30 days, the best time to monitor ovulation is usually around the 9th to 12th day of your period. The main methods of monitoring follicles include ovulation test strips and ultrasound. If ovulation test is used to monitor the follicles, when the ovulation test changes from weak to strong positive, it means that ovulation is likely to occur soon, and if it changes from strong to weak positive, it means that ovulation is complete. If you use ultrasound to monitor your follicles, it is usually more accurate and can be done around day 12 of your period, when the follicles are usually around 12mm in size. Ovulation monitoring is a way to prepare for pregnancy. During the monitoring period, you should pay attention to a nutritious diet, avoid staying up late, exertion and strenuous exercise, and keep your mood relaxed, all of which are conducive to regular ovulation.