Appeal deadline questions after an unemployment denial (update)

I was told my separation was for misconduct, which is not what happened. I do not usually post, so bear with me. My employer's version of events does not match mine, and I have emails that show it. If you have appealed before, what helped you prepare?

File the appeal before the deadline, even if you are unsure. You can gather documents afterwards. That is the one part I would not wait on.