How many mature follies for IUI?

I just had my first scan today (cd9), and I have one follicle at 11mm, the rest are smaller. This is my first IUI cycle. Will he wait till this one is 18-20 and then trigger? Or do they usually like to trigger when there are more at optimum size? And if so, how many?

[bella537]

He'll probably want to trigger when the largest gets to optimum size, the others may have a chance to catch up but they may not also but at least you'll have that one if not.

[Tanker Chic]

All you need it is one!!  Best of luck to you!!