I've gotten BFP twice with 36 hrs. I have also gotten an u/s on two different cycles approx 32 hours after trigger and follie(s) were still there. RE said you could tell they were just about to release because the edges were jagged.
My IUI was 31-32 hours after the trigger. They had instructed me to trigger 36 hours before IUI. But I had enough IUI's already that I was kinda feeling like 36 hrs was too late and we were missing the egg. So this time, I woke up at 2 am to trigger and did the IUI about 32 hours later. And it worked! I just felt like 24 hours was a bit too soon and 36 hours a tad to late.