Letrozole + Progesterone

Hey there! It’s my first cycle with Letrozole (2,5mg) and Progesterone. My doctor said that I should ovulate on cd 12-14 and then start taking Progesterone pills starting from cd15 till cd28. The thing is that I still haven’t ovulated yet and I am not sure whether it’s okay (cd15, I’ve been using ovulation tests twice a day, the dominant follicule is 21mm). I’m afraid that if I take progesterone before ovulation it could mess up with it. Is it safe to take it before ovulation?

By the way, is there anyone who is prescribed with Letrozole and Progesterone from the beginning? I’ve seen many people taking Letrozole but no progesterone. Thanks!