Let me first say, "Thank you" to you and your husband for all you do for our safety at home. Being a servie man's wife can not be an easy job and my deepest appreciation goes out to you and your family.
As for your son coming to you before your husband, well, that's a hard one and not one that you can control. You said your son is 9 months and your husband has been deployed for 8 months, so in essence, he doesn't know him personally. Don't stress about it. It will only make it that much harder for your husband. I personally would just act as if your husband has been around this whole time. Continue on with your daily routine and just say to your son, "Go ask Daddy for help" or something to that affect. Kids are very intuitive and if you have reservations he will sense that it might make the transition harder. You have been taking care of him alone for 9 months, let Daddy help now. And again, act natural and your son will be fine.
Cheers to you and a big welcome home to your husband.