We always go to the 6:15 show, so we make sure we are in line for the boat to FW at 5:15, just in case. We have gotten there with plenty of time to get in line to check in and walk around a bit. I like to give an hour, because you just never know.. In 2013, the boat had to make an unexpected stop at WL and we were almost late getting there, but made it right on time.
We have always taken the boat over. It is a nice and relaxing ride. Only one time there was thunder/lightening, and the boats weren't running. So we took a quick cab from Bay Lake Tower. The only thing with this, is that we had to use the internal buses when we got to FW. It was a little confusing but still wasn't a problem. We just prefer to take the boat from MK if we can.