Should we have a civil ceremony now and an actual wedding later?

My fiance and I have been together for almost 3 and 1/2 years. We got together the summer before our senior year in high school. We have a 22 month old son. I work in a hospital as a CNA in a small town and its not the greatest pay. He recently joined the National Guard because he wanted to be able to have a career and help me out financially a few years down the road when he finished his schooling that the National Guard is going to pay for. He went to M.E.P.S almost 2 weeks ago and found out he is leaving for Basic on January 10th, 2010 and that he is going to be doing his Basic and M.O.S. back to back and so he is going to be gone for 6-8 months..My fiance just got a job 3 weeks ago at a local restaurant and due to the add of income, we got cut off of food stamps. And will probably lose our Tenn Care as well. My parents are pushing for us to go up to the courthouse and get married before he leaves for Basic for the added benefits. My question is should I do it? I don't think it would really affect me having the big wedding later. And we can probably use most of my taxes and his money from Basic and MOS to pay for the wedding. I'm just really confused and don't know whats best for us as a family.