Letrozole???

I want to start Letrozole but didn’t get my period last month. Normally my periods are very irregular, I am assuming from PCOS. Technically I’m on CD 36 and I believe I didn’t ovulate this month because I had 4 consecutive days that had a high LH surge and then an immediate negative on the 5th day. Do you think it’s safe to start Letrozole unmonitored?