When is the earliest that I can test for a home pregnancy test after a 3 days frozen embryo transfer?

Patience... Patience is a virtue that all parents should seek. It is most valuable for raising children. A urine pregnancy test done correctly should give a reliable result on 2-3 weeks later (making it unlikely to be a false negative if it is negative). Hopefully, it will be a positive, but there should be no need to give it another thought until then.