Should we iui or ivf?

We had our first appointment Monday.  We already know my husband has low motility from his vasectomy reversal. Doc said if it's antibodies killing the sperm he could wash them off and do iui, if they are just bad sperm he could still do iui but he didn't seem hopeful. He said he wouldn't do more than 4 iuis then go to ivf OR we could just do ivf. He said if we do ivf I could be pregnant within 2 months, if we go through 4 iui then ivf it would be approx 6 months before pregnancy. Part of me wants to go straight for ivf bc then i would have a sept/oct baby, I really don't want a dec/jan baby bc literally everyone in my family is including my 2 step kids. If I did iuis first, dec/jan baby might just be in my future. I know I should just be happy with a baby regardless of their birthday, what would you do?