If you are on fixed dining on a cruise, there is an etiquette to follow when it comes to time keeping. Fixed dining is still very common on most cruise lines. It means you are allocated a set table and time for your evening meal. You will dine with the same people and have the same serving team each evening.
It is important to arrive at your table as close to the starting time for the meal as possible. Some lines offer up to a 15-minute window before they will, in theory, not allow you to join your table. If you arrive late you hold up the meal for everyone at your table. The servers aim to ensure that everyone receives the starter, main course and dessert together. So they will wait for everyone to arrive before taking orders or, if they have started serving, they will then stop serving the courses until everyone has caught up. This is to make their work load more manageable and reduce the number of times they have to go to and from the kitchens.
If you are on fixed dining it is courteous and good habit to be on time.