not to be very contrary

but since this is your first cruise and you are flying...
- I would not worry about pirates costumes ... single use clothes that take up space ... unless that really floats your boat

- I would not join up with a fish extenders group (gift exchange) ... will take up luggage space going and coming. But there are a lot of people that love them. You should have time to find an join a group before your cruise. If you participate - it will take you a while to wander the halls and deliver your gifts - and you might want to be doing something else.
Stuff to do now
There are lots of good hotels in Cocoa Beach. Are you planning on driving to the coast from the airport? The Cocoa Beach / Port Canaveral tourism "board" has a package that will pick you up at Orlando Airport, Drive you to your hotel in the Port Canaveral area, then on the morning of your cruise shuttle you to the port. We used it a few years ago ... worked out pretty well.
GoPortCanaveral
RE: Activities: you should be looking at
DCL's web site for Port Adventures for the ports you are going to. Decide which one(s) you would like to do and can afford (some are WAY expensive), then do your research on other independent touring for those ports - if you are comfortable going out on your own. There are a lot of people here that go out on their own and can give a lot of good recommendations. Remember, the ship will wait for you if your excursion through the ship runs late, if you are on your own, well
Rule number 1 is Don't Miss The Ship!! Rule Number two: Know When All Aboard Time is in every port. Rule Number 3: Keep your watch / cell phone set to Ships Time... 99.999% of the time it is local time ... but NEVER rely upon that. In your stateroom there will be a notice to change your clocks forward or backward on the nights when you need to do that.
I will Second, Third and Fourth: that you find your needed Government Documentation - NOW!!!
Put it somewhere safe that you can get it any time. And verify that its valid for the travel (and time) that you will be embarking on. There have been stories over the last 20 years here where people have said to themselves - my passport is in the safe deposit box at the bank. Not a Problem. Until they are getting ready to leave on a weekend or holiday .. or a "sneaky" bank holiday - think Columbus day - when you can't get your doc's and your flight leaves in 4 hours

For the kids - you will need a valid birth certificate (passports if you have them are always better in my mind). The adults will need either a passport or one of each of the following: Birth Certificate and Photo Government ID (ie Drivers License), again, I prefer to travel with my passport. If you are using your passport to get onto the ship, Adults should also bring their drivers license - to get back into the port area after your day on shore - for getting on the ship the Drivers License is easier than the Passport.
Things to do in the weeks before you leave
Other people might suggest you find prior Navigators online to get an idea of the activities onboard. I say - skip that, leave some "surprises" for on the ship. Same goes for the menus .. why decide what you want to eat before entering the restaurant. Speaking of Navigators, you can
now Download the DCL Navigator App (Android and Apple). Do it before you board the ship. Then onboard it will give you all of the days activities (actually will show the entire schedule for your cruise).
I would call DCL and ask them what the "theme nights" are for your cruise ... as you get close to Sail Date. We do this to help with our packing. Nice to know what nights are Formal, Semi Formal, Casual, Pirates, Frozen, etc. Also we check the weather where we are going the week before we leave - again to verify what we packed. Our last cruise we were touring for a week before the cruise and the weather forecast for our ports and was mid to upper 60's. Well in the week prior to the cruise portion, the weather cleared up and the temperature dropped 10 degrees, so unfortunately we didn't have heavy enough coats to be out on deck for very long at a time. I'm guessing that you are doing the Caribbean or Bahamas cruise - so the weather will be more predictable.
And you can start practice packing now. Then get rid of half of the clothes. And frequently that will still be too many clothes.
You do NOT need different shoes every night!! (oops, that's the frustration I have with the females in my family ... you're fine)
Have Fun!!! It's good that you have Thanksgiving and Christmas (and various other celebrations) between now and the cruise. Waiting for embarkation day is HARD!!
Last Advice for New Cruisers
- You Can't Eat It All - but try new foods onboard- if you don't like it your severs will bring you something else - it won't cost you any more money
- You Can't DO It All - but sleep is for AFTER the cruise. And I find that I could sleep my cruise away ... the usual gentle rocking of the ship, the comfy beds ...
- Sunscreen - Fully, and reapply Frequently ... The Sun
IS different there than where you live (usually) and especially at the time you are traveling. Sunburns cut down on the fun by A LOT!!