On average most women ovulate 12 days after the start of their most recent period on a regular 28-30 day cycle. Although it also depends on your cycle length some women ovulate 20 days after their first day of their most recent period. (30-40 day cycle) Your best bet would be the ovulation test sold over the counter if your trying to get pregnant. Most dra recrememd to have sex up to 3-5 days after the end of your period for best chances of possibility becoming pregnant. But again, it depends on your cycle