That's a good run down. Thanks. When is the prom? How much time before the big night?
Just to be clear, when I said PRACTICE, I meant as soon as possible, several DAYS before the shoot, not an hour.
Then, you should get to any shoot at least an hour early (or more) to set up, prepare, make sure everything is good, etc. I could write a list but in general you should be ready to press the shutter at least a half hour before anyone is due to arrive. Then you can relax, casually go over your plan and get 'in the zone'. What people will interpret as a skilled photographer on a shoot is how prepared and smooth you are, not how good the pictures are. (That comes later!) If you are still setting up, can't find things you need, tripping over your gear or yourself and appear confused and stressed, this is bad. What you are shooting for (pun alert) is cool, calm and collected. Easy going, fun and cheerful. You are a master of all things photographic, technical and spiritual! You make the birds sing, the clouds part and the sun vary its intensity and white balance with a wave of your hand! ........... OK ........... I got carried away. No one can make birds sing.
What I'm trying to say is that the practice session DAYS AHEAD OF TIME will help you be experienced and organized. You'll know what to expect, you'll have a solid plan that you are CONFIDENT will work because you already tested it, proved it and you already know what images your poses, your camera settings and your plan will produce! Without proper planning and practice, you are lost.
I can tell you that regardless of age, experience, talent or skill level, everyone gets nervous. But that soon goes away when you get rolling if you are well prepared and you have a solid plan to follow. And don't be too surprised when things don't work exactly as you expect. This is also normal.