read this po mommy: https://www.africaparent.com/when-does-ovulation-start/ it has a part that says: Different ways of calculating fertile days to know when does ovulation start Ovulation is also called the fertile period. During this time, there is a high chance of pregnancy if the woman has sexual intercourse. • For most women, ovulation occurs between day 11 and day 21 of their menstrual cycle. To get an accurate number, count 11 days from the first day of your period and you’ll find that your fertile period falls between then and day 21 • You can also predict ovulation and fertile days by counting 12 – 16 days before the beginning of your next period