when can I test

Paige
AF isnt due til feb 7 (day 34 of my cycle according to glow)...but I am already 15 dpo....tomorrow is 16 dpo and 6 days before af is due...would that be an okay time to test? 
I've already got two negatives this month. I don't want to keep disappointing myself but also I want to find out as soon as I can.