We have been cruising with our boys since they were 5 and 8.
The youngest is now 16, so they have been through every age group of Camp Carnival.
22 cruises later, I have to say that Carnival has consistantly done an excellent job with them. The youngest has Autism and Carnival has gone above and beyond more times than I can count.
Your 3 year old will be in the 2-5 age group.
You will have a pager should they need to get ahold of you.
There will be an Orientation on Embarkation night. (usually around 7pm) The exact time and location will be listed in the Caper (ship newsletter) waiting in your cabin when you arrive.
The Orientation is to introduce the ladies who will be caring for your child and to fill out one slip of paper...allergies etc.
At this young age, I would suggest that you hang around AFTER Orientation and spend a few minutes introducing your child to their specific counselors.
There will also be an ice cream "get to know us party" later that night...but it is usually very hectic and high energy.
Your 15 year old will LOVE Club O2.
He will also get a Caper with a list of activities, times and locations for the ENTIRE cruise. He can pick and choose what he wants to attend. There is also a short orientation for them on Embarkation night. I have seen it as early as 5:30 and as late as 8:30...it just depends on the director.
Camp Carnival will "open for business" at 9AM the next morning. On Sea days they usually close from 12noon -2pm for lunch and 5pm-7pm for dinner. Until 10PM it is all free. However, past 10PM, there is a $6 an hour babysitting charge. They are open until 3AM.
On Port days, it is done a little differently because people are taking excursions and "some" (I never did) leave their children on the ship.
So they basicly open at 9AM and close when the ship leaves port for an hour for dinner and then open back up until 10PM.
Again, your 3 year old will also get a CAPER for the entire cruise for their age group with all the Sea and Port times.
Adult Capers are delivered DAILY...where Camp Carnival Capers (as I said) are for the entire cruise.
Be aware that your son (15) will have access to a machine where he can charge $5 a day on this Sail and Sign card for arcade tokens...so if you don't want him doing that...you need to have "the talk". Or you can go to the Purser's Desk and have his Sail and Sign card "deactiviated" so no charges can be put on it.
Have a great cruise!!