The SAs will typically have someone dedicated to prior enlisted admissions, and they should not be surprised by other-service applicants, even if their focus is enlisted from their own service.
I would start with USAFA’s Admissions POC for enlisted, as well as your own chain of command, including the career counselor. No doubt about it, should you be successful, paperwork must be done!
https://www.academyadmissions.com/admissions/advice-to-applicants/enlisted-airmen/
I know you are not considering USNA at this time, but there is a senior enlisted advisor in Admissions there, and “asking the Chief” is never a bad choice if you get stumped on Navy-side process. You can simply call or email Admissions and ask for the enlisted advisor.
https://www.usna.edu/Admissions/Apply/Active-Duty-Service-Applicants.php
Be sure you allow for the likelihood of a year at prep school before actually reporting in, so that you are not over the age limit.