Appeal deadline questions after an unemployment denial - first time posting

My claim was denied after 12 weeks of waiting, and the letter says I have a short window to appeal. It has been weighing on me all week. My employer's version of events does not match mine, and I have emails that show it. Did you bring documents or only talk?

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.