Let's see, we'll be celebrating;
You'll have one big problem here; 4 night cruise. I've done a 7 night last year for the first year. And be ware; 4 nights will NOT be enough. Even 7 weren't. First and last day will mostly be lost with arriving, leaving, getting things sorted etc. You'll finally get into the mood and have to repack again

Prepare for the bummed out feeling when you realise how quickly it all goes by.

That, enjoy Palo (VERY much worth it, incl. brunch and high tea), use the room service and if you're considering doing a future cruise; rebook while aboard! They'll give you a discount and onboard credit. That will be the best price you'll ever get. In the small odd prices decrease;
DCL will still match. For more OBC you can still transfer such a ressie to a
travel agent and you can cancel free of charge, just like any ressie made on land. Don't be one of those many folks considering rebooking, not doing it aboard and running out of the extra % off for booking aboard. It is a very risky thing you're doing, too many folks will find themselves addicted afterwards. Not a very cheap addiction.