You have a CA hearing in 6 days. You need to get your ducks in a row as based on what you say happened. It doesn't matter WHAT day you got the actual warnings. A typo, as it has been pointed out, is not going to change the whole story, exactly what happened in January, and what actually happened on the incident immediately before you were fired.
The question, or issue, is going to be "did this person have warnings that his/her behavior was not acceptable, and then in a final incident, he/she did the same thing again, which was try to defy the manager, explain to him what his job was, and be insubordinate to him as they were attempting to get the work done?" Fix it so it doesn't sound this way. You'll get your chance to tell your story.
I don't think I'd make any kind of big deal about what actual date these things happened on. You yourself admit there was some sort of issue that was had in January during the visit of the regional manager. Exactly what did happen then I cannot figure out, but it would be to your advantage if you can truthfully state that during that visit you were NOT warned that you were treading on the ground of trying to take over the manager's job, which is frankly what it all sounds like. If a manager is "trying to get you fired" make no doubt about it, they can do it, legally, too. Just because you felt you could do the job better than they could, and felt led to share with them how you thought the job ought to have been done doesn't clear you. Certainly not that they report this incident happened on the wrong day. But the whole issue is, did they, did anybody, at this time, tell you to back off and do what the manager told you to do?
Then on the last incident, the incident that precipitated your firing, was this insubordination? Really? Think how you can describe this in some other way. This about the most positive light you can put on this whole incident. You informed the manager that he had done the wrong thing by posting the maintenance order on the tenant's door, right? You were trying to help, trying to get the job done right, weren't you? Memorize this phrase, "I always did my job to the best of my abilities."
You may point to the incident of the Christmas decorations and try to put it in a positive light, but frankly, you had been told NOT to decorate, and you went on and did it, at your own expense. Don't even bring this one up if they don't because it makes it look like you were trying to take over this manager's job and tell him how to run the facility. That's considered insubordination, and may cost you your job without unemployment insurance. Don['t whine about how this new manager didn't like me, had never liked me, had had it in for me because.... it's your job to do what the manager wants, even if he's a total incompetent.
Be careful to emphasize your interest in doing a good job, how long you had been there, doing a good job, how you tried always to do the job right and to the best of your abilities, and you never refused to do your assigned duties or a direct order from your manager.
Keep making your certifications until after the hearing, so that if you win in this decision you can be back paid for all the weeks before that you have filed for.
Be polite, professional and to the point in your hearing. Listen carefully to the questions that the hearing officer asks you. Do not speak out of turn. Say over and over, any time you can work it in, that you did not mean to be insubordinate and that you always did your job to the best of your abilities.
