I'm a guy, but I can tell you this: Go there, have fun and meet your friend. Try to be positive. You could tell him that you sometimes stutter if you feel like it. Try to be calm, breathe and talk slowly. If, for some reason, the date doesn't go as planned, don't worry, it's still fine: In fact, you will get some experience that will help you in the future. The important thing is trying and facing our fears. Good luck!