Appeal deadline questions after an unemployment denial - 13 months and counting

My claim was denied after 13 weeks of waiting, and the letter says I have a short window to appeal. The letter lists a deadline and a hearing process, but it is hard to follow. 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.