I meant to post this update here, first, but I mixed it up with the Shuffle thread:
I found out from my manager that I can do this on a couple conditions:
1) I can only request a day off everyone once in a while. It can't be every week or every other week.
2) I must request a day off at least 2 weeks in advance. The longer the distance between when I request a day off to when I reach that specific day, the more likely I will in fact get that day off.
3) Reasons and priority: The more important my reason is for taking the day off, the more likely I'll get it off, as well.
Because of this, I'll use this to go to Phoenix Saga 6 on December 7th, but even though I requested it this early, I might STILL not get it if someone else requests that same day off for something like a funeral.