You can already book your MSC Meraviglia cruise for 2017, giving you the opportunity to get the stateroom you desire, although we already know that these cabins have started to book up fast. The new ship is due to enter service in May 2017 and will only sail to destinations in the western Mediterranean.
From what we can see so far there are only 6 MSC Meraviglia itineraries for 2017 at this time, although we know that more will be added at a later date. You could take the chance and wait for more to become available, but it is always nice to get on one of the earlier cruises of a new ship, as things have a much better feel when brand new.
There are several MSC Meraviglia booking options that you can narrow down for your 2017 cruise, although you might not want to select any seeing as though there are only 6 cruises on this new MSC cruise ship to begin with.
Those 6 cruises are offered in more detail on THIS PAGE, where you will see details on each cruise. Some of the ports that Meraviglia will visit include Genoa, Naples, Barcelona, Marseille and many more.