IUI sooner than I thought

JBo
Im cycle day 11 today and had my US. 4 follicles over 14mm and one of them already 21mm.  My RE wants me to take the trigger shot tonight with IUI on Wednesday mid-day.  Its 2 days earlier than I thought.
Nervous and excited.  My RE pretty much told me I only have a 5% chance due to my age but I am hopeful to beat the odds.  Wish me luck! ❤️
UPDATE:  I have been testing since 10 DPO and all negative.  AF due tomorrow or Friday and I think I feel her coming.  I hope others are having better luck!  :-(