Getting pregnant right after getting married.

My fiancé and I are getting married in December! We have talked about starting a family right away. He is in the military and we will be apart for 3-6 months starting two weeks after we get married:( I don't think the chances are very high that we would get pregnant in those two weeks. I don't want to try to get pregnant but should we prevent getting pregnant? What are your experiences with getting pregnant right away?