Yes, I stuttered badly during an interview. I felt like shit for the following two weeks, but funnily enough, I didn't secure the offer because I failed the entry test, not solely due to my stutter. Since then, I try to disclose it as soon as I stutter. I say something along the lines of "Sorry, I have a stutter". Then again, sometimes it goes really well and I'm almost completely fluent. It's random. But, if I had to give advice, I'd suggest to disclose it beforehand.