Srarting letrozole!

I will be starting Letrozole soon because i have PCOS and i do not ovulate on my own. I have to have an ultrasound before starting the medication to rule out any cysts. My ultrasound is scheduled 12/13 which will put me at being on cycle day 6 cause i started my period last night. My doctor said i would have to take the medication cycle days 5-9 so will this mean i won't be able to start it this month? I've tried calling my doctor but the office is currently closed.