Femara CD 2-6 vs CD 4-8?

Hi everyone. Last cycle I did 2.5 mg of femara cd 4-8 with TI. I had two follies at O, one measured 28 mm the other 20 mm. BFN. Re now wants to do IUI with trigger shot but had me try cd 2-6 of same dose of Femara this cycle. Has anyone noticed any different between taking it earlier vs later? I am doing a Saline Test of the tubes and uterus tomorrow and checking on the ovaries before IUI next week hopefully. Any insight and experience with doing Femara on different days and what worked for you if you have a BFP. I am 37 and taking a lot of supplements to help egg quality. My AMH is 11.5, FSH is 7 which RE says is excellent and I have ANC of 30-40 in any given cycle. Polycystic ovaries present but my labs are normal and I ovulate on my own on cd 15-16 every cycle with healthy levels of progesterone 15-20 7-8 DPO on unmedicated cycles. Thanks!