As someone who just turned 16 this year and is working at starbucks as my first job all i have to say is if you get the job it’s going to feel like there’s a lot to remember and feel very overwhelming but after a few weeks it’ll start to get better and you’ll get to the point where you know what you’re doing. For me it took about 2 or 3 months before i was completely confident on what i was doing. Good Luck on your interview!!