If memory serves, I began to take it a week or so before transfer.
I have the same issue, top grade embryos but no implantation.
Last IVF I started aspirin with my stims. Actually you are not supposed to do that in IVF, but I did it as we were preparing for an IUI and it was changed into IVF at the last minute. At that time it was too late to do anything, and because of my thin blood I bled a lot in the ER procedure and it was very painful afterwards. Blood tests were also a problem as I got huge marks each time I had one done.
This time, I started aspirin the same day as my ET. But I've heard that you can start a few days before also. Hope this helps,
I take it daily because of a blood mutation problem but according to my office they have you start day after transfer. Good Luck
My RE actually had me start aspirin the first day I started Lupron injections. I took aspirin through my entire cycle up to my first u/s. Worked for me. Hope it does for you, too. Good luck!
My doc put me on asprin the day of transfer.
Day of transfer for me both ivf's
Started it while taking my injections