I'm going around the same time as you are and I packed all of my shirts, swuimsuits, Mickey ears and ponchos about a month ago lol. I usually do pants, other clothes and toiletries the night before as it's starting to get somewhat hot where I live so I'm using my shorts. I'm not planning on bringing checked luggage and instead doing a carryon that goes into the overhead so I'm currently playing Jenga in my bag to make sure everything fits xD
It's easier for me since I don't have kids and every person I'm going with packs for themselves, so I'm only responsible for making sure I have what I need. I actually like packing early, it gets me excited for the trip. Plus it gives me a lot of time to triple and quadruple check that I have everything. On my upcoming trip my group is planning on doing a stop to the Target near WDW property so if anyone does forget anything we can grab it there.
The night before I wash everything I didn't already pack so I'm all ready to go to hot/humid Florida in clean clothes. For bras, I hang them to dry on my bedroom closet door or put them on my carryon so I know for sure that I won't forget it.