Pre-receptive?!?! Long post alert

How common is it to be “pre-receptive” (or post receptive)? For those of you who don’t know what that is, pre-receptive means the endometrium is not quite ready to receive the embryo and transfer is not ideal at that time - with pre-receptive, you usually wait 1-2 more days to transfer (and post receptive means you transfer 1-2 days earlier). The only way to determine whether you are pre or post receptive is by doing a MOCK embryo transfer protocol and on the day of your transfer they biopsy your lining instead. The test is called ERA or something. So here’s the thing, I’ve read you can request this test after multiple failed transfers, or if you only have one embryo left, etc. I’ve only had 1 transfer so far, but it failed. We just started our second transfer cycle a few days ago. I only ask about this perceptive thing because in the past 6 months I’ve heard of TWO cases (both close friends) that have had multiple failures and turns out they were both pre-receptive. Basically, they wasted multiple embryos following the standard protocol and transferring them at a time that wasn’t ideal for implantation. So now I’m concerned that I’m about to waste my next embryo, and I’ll only have one left. Does anyone know anything about this pre-receptive stuff? How common is it really? I’ll bring it up the next time the nurse calls with my monitoring but figured I’d ask you ladies first. THANK YOU!