Just keep it simple. narrow down what you would like to teach, and what you need to teach.
It's easy for the me to say not to worry, but if there are things that are worrying you, make a list and erm, try to fix them one at a time, step by step and knock them of your list.
Maybe imagine the best you can and the best poissable result.
It's normal and okay to feel what your feeling,
Best of luck!
Reiki on!