You are arriving at a busy time on a busy weekend. On top of that, it's still winter, and flights could easily be delayed.
You need to allow up to half an hour to get to the luggage area and get your luggage, another half hour to do the paperwork on the rentals and laod them up, and it's a half hour drive to the Dolphin.
Then allow about 15 minutes (possibly more depending on how busy they are) to check in and get to your rooms and drop of luggage, then if there is a bus waiting when you go downstairs, about 15 minutes to get to the MK.
The quickest I've ever gotten from airport to the MK with a stop at my resort to check in was a little over an hour... I had all carryon, Tiffany picked me up, there was no wait to check in, my room was close to the lobby, we dumped the bags and went to the bus stop, there was a bus just pulling in, we had our passes already, bang zoom. That' was very unexpected and will likely never happen again!
A lot depends on luck, and what time the parade is that night. If it's 7:00pm, I think you are really pushing your luck. A lot depends on how fast your group can move. If they are the type that need to stop at every bathroom and just can't seem to operate effectively and smoothly as a group, forget it. If they are all really focused and move fast, maybe.
I wouldn't count on it though, and be pleasantly suprised if it works out.
Anne