My kid has a learning disability that causes him to read slowly and need additional time on tests and so on. Some of his upcoming college auditions include cold reading, and he is really freaking himself out about it.  How accommodating should we expect BFA programs to be? When is a good time to disclose something like this to a school?

ASAP! This is not as uncommon as you think, and almost any school will be happy to make accommodations, but communication is key. Send an email to whoever runs the audition process (the admissions office or acting department, most likely) and let them know right away. Your son should also take the initiative to mention this when he arrives for the audition so that the individual faculty in his audition are aware, but the email is important so that you have something in writing. Most schools have a student disability office/center/department, and are going to be very careful not to appear to discriminate over a disability.

At the school where I worked, we had a handful of students who needed accommodations every admissions cycle, and we were always happy to help. But it’s definitely your responsibility to let them know, since they won’t ask.