Most women ovulate 2 weeks after their period and conceive a week later (3 weeks after first day of lest period) You may or may not get a period if you have conceived. If you miss a period, it is best to wait 2 weeks to test. (You can test a day after you missed, but might not get an accurate result)
I'm not quite sure what you are asking so I will try this. You normally ovulate 7-10 days after your period give or take a day. This is when you are most fertile. If you were to become pregnant at that time wait a week after your next period is suppose to start then do a pregnancy test or get a blood test done. If you do them to soon you will not get a good reading.