It is my determined opinion that when freaking out before a public reading the best thing to do is clean your house. Vacuum, clean the bathrooms, clean the kitchens, straighten, dust. The sheer focus will be almost meditative, plus you will work off a lot of energy. Only then should you shower.
Arrive early to your public reading destination. Organize the books.
Then relax. These are good people. You love these people.
(Wanna see a me in action? For video of a little of my fancy footwork see this post by Pasadena Adjacent. I'm actually a little entranced by my shoes. )