We applied in early August last year and did not go test optional. We waited send SAT scores until she got her results from the late August test. She was accepted less than 48 hours after her SAT results were sent.
I think you should pay the housing deposit ASAP after acceptance. Yes, you also have to pay the enrollment deposit too, but our admissions rep was very open that it was nonbinding (though I did confirm that everywhere else we paid housing deposits did not require enrollment).
She applied to Blount on October 9, and received the invitation to interview on October 16. We went to Capstone Scholars Day in January, and the interview was later that month, and accepted to Blount March 1.
If your student is not going to go to Bama without Blount, then the housing deposit doesn’t matter, really. And if you are doing Honors, you can probably get a good single later in the process, but the housing part is very stressful. Fortunately you can bypass all of that hassle with Blount.