As jess said it depends on the area and how much surplus housing is available. When we lived up catterick we had surplus housing and then when we found out we were moving down south we got told they had zero surplus available. So we had to get married within that month so we could move as a family .
It depends on the area and how much housing is available. We had to wait till after we got married, and then we were able to get a move date 2 weeks after our wedding.