A new system of booking character breakfasts and a few character meet and greets is now available at your booking window via " on board fun".
Log in at your booking window, I assume 75 days pre cruise and you will see it.
I would suggest you" Google" recent navigators for your cruise, - many sites and trip reports gave these, and see what us listed for your cruise, where you are, the ship, and length of the cruise.
All character interactions will be listed in the daily navigator, and also on stateroom TV, and also on TV screens in the atrium.
Only a couple are pre bookable, most are turn up and queue.
Sometimes the characters do unscheduled walkabouts on the ship you maybe lucky, and they visit kids clubs, shows, and occasionally meals.
There is a phone number for stateroom phone that also can be called for character meet and greets.
I would suggest joining a cruise meets group for your cruise, those cruisers can guide you, and they can tell you what's on offer when they book earlier from 120 days pre cruise.