Sara - this I can help you on. I actually was a bit peeved about the first transfer. Yes it was Day 6 - and yes, they had to use a larger pipette. The embryologist said it was the biggest embryo she had seen transferred - it was multiplying rapidly. They kept reassuring me that the embryo itself was perfect. I was annoyed, as my understanding from what happened is they had already removed the cells for biopsy on Day 5. I believe they may also have dropped the DNA colour probe on it the day before as well. But this takes two hours to kick in, and it was closing time. So they were biopsied the next morning. But the FS booked to do my transfer was not available until 2pm! We arrived on time, but he was late. So 3 o'clock transfer. If only my embryo had been ready just a couple of hours earlier on Day 5 it would have been transferred late that day! In fairness, in my case, things also take longer, as I was having 8 tests done. This is done in two rounds (5 chromosone, then 3 extra chromosones) and has to be double-checked by the second scientist. Sorry about my rant, but yes, I do wonder... Now scientifically, I was told Day 5 blasts to have "a slightly better implantation rate". Apparently implantation happens around 36 hours after transfer with a Day 5 blast. I was told by about Day 7-8, the embryo loses it's quality. So in my case, my first transfer would have been trying to implant around that time.