My two pieces of advice - 1. If you see her struggling, ask if there’s anything you can do to help (some people don’t like it when you try guess the word they are trying to say, whereas others think it’s totally fine). try work out what to do and not do by asking her 2. Just listen and be patient. She’s been dealing with a stutter for all her life so she’ll know her own ways around it I hope you have a nice time seeing her. 17 years is a long time!