Correct. And you are docked pay on the back-end these days. I had Christmas Exodus during BCT, returned and graduated, then started drilling back home. My first drill pay check after that (and all of them for about 6 months) had "Debt Repayment" taken out to pay back leave.
It might be slightly different for your husband, since depending on the length of his AIT he could accrue enough leave. Even if he goes in the hole before AIT, he would still be on Active Duty orders and could have time to make up the deficit in leave. He shouldn't start getting charged Debt Repayment until he comes off of Initial Active Duty Training (IADT) orders.
At basic...ok/maybe...but it really depends on the type of order you are on. If you advance leave in a coados type status they can hold pay amd give it back as you acrue leave.