IUI Timing

I went for mid cycle scan today (Thursday morning). Follicles on left: 17, 13, 12. Follicles on right: 15, 15, 12, 11.

Instructions for IUI: Ovidrel Saturday night 11 pm. IUI Monday morning at 10:00 am. This is about 34 hours between trigger and IUI.

I’ve done one IUI before but I triggered the afternoon before and then did IUI about 24 hours later.

My question is are they having me do this since they’re closed Sunday? Is it even worth it? What if I ovulate Saturday prior to the trigger? I can already feel follicles becoming heavy. Uhg, I’m just worried it’s too late. I need reassurance that this is appropriate protocol. Thank you!