you can only test up to 5 days before you're period with a really sensitive, fairly expensive test and even then it may not pick up a positive. If you wait until you actually miss your period, you can be more confident in the results even on a dollar stores test. When you test super early, even if you are pregnant there might not be enough hcg to register. Then you end up squinting for a vvvfl and symptoms spotting.
Note* This is not a jab at early testers just my opinion from experience..