Wendy,
I am Canadian. We just got back from a 3-day stay at Disney and a 4-day cruise on the Wonder a month ago and had to report to immigration at 5:45 on the last day. That was VERY EARLY. However, it went very well (it took about half an hour), so we were able to go back to bed and get some more sleep before our assigned time for breakfast.
Hope this helps!