I am not certain about which nights for sure; however it should be per Carnival - The first Cruise Elegant evening is scheduled for the 2nd or 3rd day of the cruise; the second Cruise Elegant evening is scheduled for the 2nd or 3rd day prior to the end of the cruise, schedules permitting.
For this itinerary I'm guessing the Captain's Celebration dinner will be on Monday and the second on Friday. Nice itinerary by the way.
We picked this cruise just for the Itinerary. We have a group that has already done the Western and Eastern and wanted to do the Southern. Carnival hit the most islands during the week! And gave us a good group price....which is good too! =)