FOr a 3 night cruise - you don't have a lot of time so....
First Day:
Be at the port before noon. THe terminal there is a fun, interesting building. You get checked in, you might have some time with a few characters, then you can get on board as soon as possible - *** (Mickey Vacation Time) goes by so quickly.
First Cruise, Only 3 Nights - I'll be in the minority here - SKIP Palo. Yes its wonderful food, but it also takes twice as long as a "normal" rotational dinner. Save it for next time - because there WILL be a next time. DCL it's not just a cruise line Its An Addiction!! (like most addictions - it too is a spendy one).
You will be able to have lunch onboard after boarding - In February eating up at Beach Blanket Buffet and sitting outside can be very pleasant (not so much in August!!).
After lunch, drop you carryons in your stateroom, keep your camera, find out when an where the ships tour is - this will help orient you to the ship - its big and easy to get "lost". I assume that they still to the embarkation day tours.
Be back in your room before the 4pm safety drill. Find your life jackets, unpack your bags (DO NOT BRING TO MANY CLOTHES!!) You do not need 2 outfits per day (daytime and nighttime). OK ladies you might, but the guys can change into slacks and polos for dinner, then for the next DAY wear the same polo, clean one for dinner, repeat, repeat. You get by with about 1/2 of the clothes you think you need.
Safety drill - keep you camera close by - great goofy pictures with you and your family in those big bulky (not as bad as they used to be) orange vest. Fun pictures.
Go to the shows - they are good. Go to the Family Caberet or other activity between your dinner and main stage show (about 7:30). Go to the adult cabaret shows in the evening (usually starting after 10pm)
Next day(s) explore, relax, have fun, eat, go to the shows
Disembarkation day: hide - make them come and find you and drag you off of the ship
I have saved the best advise for last...
You can't do it all (although we want to)
You can't eat it all (we have all tried)
let the magic come to you - you don't have to go find it and enjoy the moment.
You can always sleep once you get home
and lastly, you CAN NOT stuff your room steward into your suitcase on the last night - 1) no one will carry your bag off the ship then, 2) they fit but put up a fight 3) how would you declare them on your customs form