We've not yet been in this situation and pray that we never will be. But we all know that it is a fact of life when you are living with a food allergy. Despite any personal fears, it is important that everyone develop confidence with the pen. If you don't have confidence before an emergency, you will not have confidence during an emergency.
The only way I feel more comfortable is with practice, and since you can't truly "practice" a real-life emergency with a real Epipen you have a couple of other options.
First, every Epipen comes with a trainer pen. Review this regularly to make sure you remember the steps in an emergency. Use it with your friends and anyone that may be watching your child.
Second, there are tons of Youtube videos that demonstrate how to use the Epipen. Watch several of them until you get comfortable with the process. Here are examples of a two, but there are many more:
Finally, Epipens have an expiration date. When they expire, do not just throw them away. Use one of them to practice. It is helpful to see how they truly work. Use something firm but not too thick, so you can see the needle come out the other side as well as the medicine. A thick paper plate might work (something firm like a Chinet plate). Have someone hold the sides of the plates, then puncture the plate through the middle. Be sure to keep everyone away from the other side as the medicine will shoot straight out.
I have several expired pens that I hope to use for training staff once my son enters preschool in the fall.
Once they are used, return them to the original plastic container. Because they are sharps, they need to be disposed of properly. Contact your local pharmacy and see if they can dispose of them. If not, try your doctor's office next.