Retrieval and fertilization days question

Lovely • IG: Plentifully.day TTC #4. Sept 2014 tubal reversal. Feb 2016 HSG: blocked tubes. May 2016 IVF: failed. Aug 2016 BFP turned to 4th loss
I'm wondering what the time line goes like when egg retrieval is done, Do they usually fertilize the eggs on the day of retrieval? If they do it that same day is that considered day 1 or is the next day? I hope I'm making sense lol I'm trying to see if a 3 day transfer is actually 4 or 5 days after retrieval.