I asked the same question to my advisor/conductor of my mock interview in my internship class before graduating undergrad a few years ago. He said that he didn’t think it was necessary, and it shouldn’t be used against me, but it couldn’t hurt, my main concern was i didn’t want the interviewer to think i was just incredibly nervous, and possibly count it against me. I have also had a therapist tell me that it could help your fluency during the interview because once you openly mention the speech impediment, it might ease your mind a little bit now that you’re not wondering what they think as much. of course both answers were given to me much better than i just summarized them, but it’s been several years and i’m exhausted at the moment lol. so if you wanted my personal opinion, i think a quick mention of it could be beneficial, just to clear up any confusion the interviewer might have, and help you say what you want to say. best of luck! let me know if you have any other questions!