I will test tomorrow morning at 10 days past transfer. My rear end is so sore and I don't want to waste any more meds. Beta is Monday but I think 10dp5dt will be a reliable indicator. I got a strong positive with C at 10 days past so here goes nothing.
If this doesn't work, I'm thinking of pitching a "Buy 3 FETs, get the 4th free" promotion to my clinic. Seems totally reasonable, right?