Hey man, I just turned 18, have a stammer (obviously) and work in retail! I actually just started less than 6 months ago and felt the exact same way before applying for the job, and I tell you, don't put pressure on yourself if you currently don't have one. The job that I'm in is actually my first proper job too and I'm actually so glad for it as it almost forces me to be social and work on improving my speech, whilst earning a decent wage! My advice is, just go for it! And don't beat yourself up if you stutter on words or don't get the job. It can be stressful from time to time but that's part of the fight!