How effective is a pregnancy test in the middle of the month?

Molly
I know it takes about two weeks between having sex and actually becoming pregnant, provided the egg was fertilized. I'm in a bit of a pregnancy scare and I have two pregnancy tests, but the box reads that it's most effective the day before or day after the expected period. And that it's only 50something% accurate four days before the expected period. If I took one now (my expected period is in two weeks), would it be accurate?