Transfer takes place after ovulation. For a blastocyst transfer - it will be on day 5, others take place on day 2 or 3. Whatever stage the embryo is at, it goes back in that many days after ovulation.

Have you talked about the spotting with your FS? I'm no expert, but it doesn't sound like a good thing to me! I actually recall my FS asking me about spotting before AF, but I don't have any more than one day, really.

BW