1 So, the earlier after a missed period you take a HPT, the harder it is to spot the hCG. 2  If you wait one week after a missed period to test, you are more apt to have an accurate result. 3  Also, testing your urine first thing in the morning may boost the accuracy. So, home pregnancy tests will be accurate as soon as one day after a missed period for some women but not for others. 2  How you use them – Be sure to follow the directions and check the expiration date. 3  When you use them – The amount of hCG in a pregnant woman’s urine increases with time.