Appeal deadline questions after an unemployment denial - first time posting

My claim was denied after 21 weeks of waiting, and the letter says I have a short window to appeal. I do not usually post, so bear with me. I have not done a hearing before and I am nervous. 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.

I printed my emails in order and wrote a one-page timeline. The hearing officer kept going back to it.