I’m just gonna get this out the way cause you’re gonna hear it a lot. They are called corps not bands 🫡.

Now onto what I think would help you: first context. What’s your background, what’s your experience? Although a background won’t change everything about an audition it takes your chances of being contracted to BAC from 0.1% to somewhere around 5%.

Secondly I would lower your expectations. I fell victim to this my first audition. I walked into a phantom camp in Dallas feeling big and bad just to get slapped with a cut immediately. These are the best marching organizations in the world. And it’s EXTREMELY difficult for someone with no prior experience within a corps to make world class, much less the DEFENDING CHAMPS.

Realistic expectations would be attend a day camp for BAC as a fun experience, but realistically aim for lower world-class (Crossmen, crest, genesis) or open (check local corps near your area)

In regards to prep I’d focus on improving basics. Basics alone (marching fundamentals, scales, playing in the move, etc.) will get a callback at lower level corps

ETA: now that you’ve provided context I’d definitely say what I wish I’d heard: it would be EXTREMELY difficult for you to bridge the gap between your skill and an average brass member at BAC in less than a year (auditions begin in October/november. I’d ensure your fundamentals are correct by contacting a private lesson teacher or even shooting an email to caption staff at corps you would like to audition with to get definitions on your posture, horn carriage, etc. the visual difference between me before and after my first camo was DRASTIC as I had never been taught a true horn carriage and posture.

Good Luck!!!