By AIT, I believe you are talking about being fresh out of Army Basic Training. Your home address that you enlisted from stays the same. That includes everything on your debit/credit cards, and any other bill you may have... unless you update that. I do NOT recommend you updating your billing address to your barracks address until you PCS to your duty station and get settled in there. The mail rooms in TRADOC are notoriously slow, and it is likely you will not receive letters or bills on time. Keep it at your home of record, and just have someone there open it and send you photos of it. Trust me... I know.