Living out in town is not an option for you and your family until you complete A-School and Power School. I only know one married student who lived off base through A-School and Power School, and that was only because he and his wife had plunked down like 20K and bought a house in the area before he even arrived here from Basic.
Once you graduate Power School, you can move and live wherever you want. I'm about a month into Prototype down here in SC and my hubs and I didn't even consider moving out of base housing. While it is a drag knowing that your $1138/month BAH is paying for a house that would probably rent for half that price out in town, there is a convience factor to consider. Water, trash, electric, etc. are all included in your rent, which you don't even have to worry about paying because it comes right out of your check. The maintenance office mows your lawn for you weekly. Base security is always driving up and down the streets, and they crack down pretty quickly on anybody who is trying to solicit door-to-door (big no-no on base).
Housing is also nice because many of the people you will become friends with will live right down the street from you. Additionally, with a child, it would probably be cheaper for you to live on base anyways (I heard they generate a lot of extra utility usage

). The NEX, the commissary (grocery store), the gas station, the post office, the gym, the library, etc. are all within walking distance.
They are moving people into the new housing units, which are gorgeous, but I'm not sure if you would be given a new house right off the bat upon arrival or not.
Hope that helps. If you have more questions you can PM me or shoot me an e-mail at navynukeprincess@yahoo.com.
P.S. - What the other guy said about you arriving here is true. You will only be here a few days before leaving to go home and move your family down here, and you will not start A-School until your family is moved down here first. They pretty much help you out with everything you need to do to get them moved and settled.