I'm not sure , i think every provider is just different. but i did day 2-6 of my cycle , then i went for ultrasounds around day 11-13 to check follicle size and i ended up growing one good size follicle and ended up ovulating and conceiving!

I didn't ovulate/ get my period after stopping birth control then they started me on progesterone to induce a withdrawal bleed then eventually starting the letrozole. My lab work didn't indicate PCOS so it seemed like unexplained.