@nattie84 appreciate the info and I've already read that, read all about it before seeing my doc the next day and I'm going to listen to my FS. He's been doing this for years and I trust him.
The cell count can be higher at the time of transfer/implantation and for me that's much earlier than day 22-24. Doesn't meant they can't detect it earlier. My FS has had patients he's detected the cells with, treated and got pregnant so he's done the biopsy before and I trust his timing.