Most of the baris that audition don't play baitone full-time. A lot of us play trombone full time, but there is also usually a large amount of reed players that switch for the summer. You already have a step up on most people because you'll have been playing Bari non stop from summer till auditions. Although the musical audition is super important it's generally known that for baritones the weaker players can make it if they have a strong understanding of theory and look good visually. The staff understands that you'll get wayyy better at actually playing once move ins start, but you still have to show that you have some musicality at the audition. People that switch from reeds to brass (if they make it) are usually on third because their range isn't that great, so if I were you I would focus on getting my lower range down and being able to smoothly go from partial to partial. Valve consistency is also a super big thing because again, most baris don't regularly play Bari. So if you can get confident in your fingerings and be able to sight read without fumbling your fingers you'll be in great shape. But seriously best tip: if you cannot hold your horn up, you won't make it. The staff will say a million times at auditins that the Vanguard organization never looks weak, so definitely practice holding your horn up for long lengths of time (if you can get to 7-8 mins you'll be okay for auditions). Don't freak out you can totally make it!! Just don't goof off at auditions, don't talk, stand up straight, and don't look nervous!!