First, I am sorry to hear you could not get seen at Mayo Jacksonville - with the high demand for specialty services, and the limited number of doctors, it seems like many clinics are at capacity. You could check the other Mayo Clinics, NJH, and UT Tyler in Texas, but I would expect a wait at any of these as well. The one thing I can tell you is that NTM/MAC grow very slowly, so a few months delay in getting a second opinion is probably okay.

You say that you are trying to decide about starting the antibiotic regimen - have you read this information from the American Lung Association:
https://www.lung.org/lung-health-diseases/lung-disease-lookup/nontuberculous-mycobacteria/learn-about-nontuberculosis-mycobacteria
In the meantime, what airway clearance techniques are you using to keep your lungs as clear as possible?
Sue