Make him apart of the expierence, make him feel important with big sibiling duties and helping with every possible thing! I have a 13 month old and am 22 weeks pregnant and I can already tell you my son will be a jealous mess once the baby comes! But all you can do is focus all of your attention on them now and give equal, but different types, of attention once the baby comes. I was a big sibiling and I remember how important I felt when I could help mom make a bottle, throw a diaper away or grab things for her. (: