@StephyG - I can't exactly remember about the nasal spray, probably in one of the booklets somewhere, or was it meds, etc. I think it was meant to control to hormonal spike, acts like antagonist. Got to go home and check. It was one of those things they have to tell you before you give consent to the process - like a warning that one of the side effects of IVF is ohss and if it happens, you may require additional meds. Oh, and this needs to be paid for (cannot be bulk billed, that's why they are obliged to tell you at the onset). I will go home and see if I can find the info on it.
Most people, from day 1 injections (which is also CD1 when AF arrives), get an average 3 scans and BTs before you are instructed to trigger and go for EPU. For me, I had only 2 scans. By the second scan, my hormones must be spiked quite a bit (hence the ohss) that they asked me to trigger that very night.
The ohss meant that I had to cancel my ET from last cycle and I have to wait one whole cycle and can only start on the next. So at least 2 months from EPU. If you scroll back, you will see my whine and rant about this. They treat FET as a new cycle, so you can't do it immediately back to back - Medicare dictates that there has to be 31 days in between, so you are looking at 2 months at the very least.
My point is - don't come down with ohss, so definitely talk to the FS about this. Find out everything you can from the FS.