Lucky you have the opportunity at all. I have only had a couple jobs exceed a year because people are awful. No matter what I do! The only thing I can do for an interview is drive around a little beforehand singing music that even if it isn't my favorite I will actually sing to emphatically (even silly) to get myself coordinated. It seems to help me for 15-30min and if the interview goes well I seem to manage til the end. Always gotta tell them beforehand though to explain the ums anyway.  Congrats on getting the interview