Depending on how severe your stutter is, I would notify them ahead of time. Second bit of advice might not be too helpful, and it may just come with time but.. try not to give a shit. I understand you wanting the job, and job interviews give inherent anxiety but, at the end of the day, you are just trying to get your personality and professionalism across, and telling them you'll be able to do the job well. That's all. Try not to worry or panic. Try to clear your mind and lessen your anxiety (if you can). You got this, we have all been given such a unique trait (even if it's a negative one) and try to use it to your advantage.