Doctor wants to do IUI 12 hours after trigger

sara

I took an opk earlier and it was almost positive. Called the on call doctor and she said trigger tonight at 8pm and come in tomorrow (Sunday) for <a href="https://glowing.com/glow-fertility-program">IUI</a> at 9am. Why wouldn't I go in Monday which would be 36 hours. I'm confused and idk if I should call the on call doctor AGAIN.