CD 10 - First IUI!! 3 Follicles

I am doing my first IUI this month, medicated with Femara, and just had my first ultrasound today on cd10. Nurse said she saw 1 follicle on my right ovary that was 19mm and 2 on my left - 15mm & 16mm. Today is Friday and she is planning for trigger shot Sunday with IUI Monday afternoon. She did say to do an opk test tomorrow (sat) and to call her if it's positive, so I think there's a possibility that the IUI could happen on Sunday. I am a little worried that we'll miss my ovulation as I've seen girls on here that get the go ahead to trigger once they have one follicle at 19mm? I feel like I want to do an opk every minute to make sure not to miss it!!! Any cycle buddies??