Can i take a pregnancy test before missing period? if so how soon after sex can i test?

If you have regular cycle 28-30 days, it can be done after day 15th since the last sexual contact.

The earliest you might get a positive test would be 10 days after intercourse, but it might be as long as 15 days. The home tests could be positive 2 or 3 days before you would miss your period and a blood test could be positive slightly earlier. However a negative test this early might be a false negative.