IUI monitoring ultrasound, HELP!

I’m going in for a monitoring unltrasound for my IUI tomorrow. I took 5mg of letrozole from CD 3-5. This is my first cycle using letrozole and my first IUI. Tomorrow will be CD 10 and if my follicles are mature enough, we will do the trigger shot tomorrow and the IUI on Saturday. My question is, I’ve always had very regular cycles and typically ovulate on my own on CD 13 or 14. On letrozole, do we think my follicles will be mature enough to do the trigger shot on CD 10 and IUI on CD11? I was reading that a lot of people need to do a couple of monitoring ultrasounds before the trigger shot, but my RE is a 1 1/2 hour car ride, then a 1 hour train ride, and a 12 block walk from my house. I literally have to leave my house by 6am to make a 9am appointment and take a full day off work each time. So having to go back for additional monitoring is really difficult. I’m just trying to gauge the situation because I was under the impression that it would be tomorrow and Saturday, then I’d be done. But now it’s sounding like I might have to go down a couple more times… any experience with IUI and monitoring ultrasound would be greatly appreciated.