I've read that abstaining more than 1 or 2 days isn't a good idea, cuz, yes there are more swimmers, but the motility and morphology may be compromised. Not sure why, but that's what I've read. HTH, and good luck with IUI...hope you get your BFP soon afterwords...babydust to ya
My RE said 1-2 days is best.
i was told by my RE that 30 - 40 hours after the HCG shot is when you ovulate. As far as the timing of bd, i do not know. I was curious about that myself. Good luck!
I would not bd before the IUI. Wait until afterwards.