How soon can you take a pregnancy test after implantation has occurred?

There are tests on the market that you can use 5-7 days after intercourse (ie before implantation which happens around day 8). But not all tests can pick up HCG this early. Most tests will only work around the day of your due period (around day 14). Therefore go to a pharmacy and check out all the tests. Pick the early testing one if your period is not yet due. Two weeks after implantation has occured.