Carefully check on your ticket what time embarkation opens AND closes.
You don’t want to arrive 5 minutes after boarding has ended, as they will not permit you onto the ship, no matter how close it is to the closing time.
So double-check that you have the correct day and time and don’t forget to factor in the travel time to the port, bearing in mind that traffic in the area may be more congested than usual with everyone trying to get off and onto the cruise.
If you want to avoid long queues at the check-in, plan on getting to the terminal when boarding begins. Lines also tend to be shorter within the last hour of boarding, however cutting it fine is not always recommended when you live in highly populated areas and the traffic is unpredictable.