When to take a pregnancy test?

Brittany • 20....married since 7.16.14. TTC #1.
Im confused on this whole taking a pregnancy test thing. I am TTC but I've heard that your suppose to take a PT the day of your missed period then I hear your not suppose to take a PT until your AF is 2 weeks late...... help please? How many DPO am I suppose to wait before I test? And what brands are best? Thanks