On our first cruise, we stayed at the Radisson at the Port, and took the shuttle. We were on the 1020, and there weren't many people in the terminal...great for taking pics, but I, personally didn't find much to do. I didn't need a snack after having a buffet breakfast, and certainly didn't need one before getting on a cruiseship! ;-)
There were people checking in, but they also have people that try to intercept you at some work stations like they have in banks, to go over your paperwork so everything is ready when you get in line. We were bored to death at the terminal, so we've never gotten there that early again.
They start letting people on the ship just after noon, if all is going well, and there are VERY few chairs, with none in "line". I decided I didn't need the back problems I get sitting on the floor, another reason we don't get to the terminal too early.
HTH, Kelli