I'll give my opinion but please understand that I'm not trying to tell you what **you** should do, just what **I** would do. I don't think you should warn the school ahead of the interview. I think the school, the interviewer and yourself should treat your stutter as a very minor thing. The least importance you'll give to it the least of a problem it'll be. People doing interviews are used to talking with people that are under stress anyway, don't assume you'll be the first candidate they see with a stutter. If you want to mention it during your interview, you could argue that your stutter slows down most communication with people, giving more time to think about what you're saying and more time for the customer/patient to think about any question they may have. I've had multiple interviews in my life and I've stuttered in everyone of them. I've never felt like it held back my candidacy in any way.