Your hands can shake and still sign up. Nobody checks for steadiness at the door.

Nerves are not a qualification test. Your hands shaking means adrenaline is doing exactly what it does before something that matters, and it says nothing about whether you are ready or allowed. There is no one at the entrance checking your heart rate. The people who look calm doing this mostly learned that the shaking and the doing can happen at the same time.

Sign up while you still feel unqualified. Fill the form in, put your name down, send the message, with whatever your hands are doing. Steady is something that arrives later, usually after you have already done the thing a few times.