I think it's really up to you -- I don't really like advertising my stutter because, as one of the other posters said, I don't think I need to apologize. By analogy, I think it would be weird for someone to point out another characteristic, like "just so you know, I'm bald or have anxiety issues, etc.". I guess I just figured they would pretty quickly tell that I am having difficulty speaking and there wasn't a need to explicitly state it. I just try to have a positive, cheery attitude and act like this is normal and not a big deal. If the person asks, I'm honest and upfront about my stutter though. Some people love self-advertising though, they feel like it relieves the tension of the situation, you just gotta see what works for you!