Best time to take a Pregnancy Test?!

Laura
My husband and I decided we were ready to TTC! And we are both soooo excited! 
I'm not sure the best way to keep up with everything though!
When's the best time to take a test? 14DPO? Or 14 days past the sex? Or only after a missed period?
And how many of you ladies still had your periods the first month or so?
I'm so ignorant! Lol. Educate me!
Teach me your ways.