Pretty much, you won't be able to file anything until you've established residence in AL. I'm not sure how long that is in AL, but a good guideline is 6 mos. He would need to establish residence in MO before filing.
It's 6 months in one county. you have to file in that county in AL. you will also need an affidavit from someone who knows you saying you have lived in X county for the last 6 months. BTDT.