I vaguely recall that with HRT FETs, you will take various drugs and have a scan to determine when the uterine lining is thick enough for transfer and then things go from there.

BW
Yep I'm doing my first FET I'm on the pill then I stop that for 3 days and they've given me progynova tablets (I think it's 3 a day) then I have to have a scan to see if the linings thick enough then progesterone pressaries