When to test

So I've heard about it all and I'm curious which is the best, AF is supposed to be here in 8 days and I'm really hoping I don't get a visit from her I'm anxious and want to take a test but I'm not sure if it's even worth it yet these are what I've heard are they true ? 
- two weeks since last period 
-5 days before missed period 
- two weeks after ovulation