For the OP.... don't pay too much attention to what the Flyer says. Cruise lines provide arrival times at ports to passengers so that they can make some reasonable arrangements regarding their schedules. The cruise line/captain is not going to burden you with all the operational and bureaucratic detail about pilots, line-handlers, immigration and customs clearances, etc... and leave you wondering what time you should 'actually' be planning to be able to go ashore.
Of course, you'll have to wait until you're given direction(s) on getting off the ship; you can't just head towards the gangway until everything is ready. Don't worry about that though, crew members will politely tell you to get lost and wait elsewhere until the all clear is announced.