Our flight lands at MCO at 6:30pm
You probably mean that your flight is SCHEDULED to arrive at MCO at 6:30 p.m., not that you will land (touch down) at 6:30 p.m.
You could be at the gate with the aircraft door open as early as 6:15 p.m. if the flight departs on time. That's because airlines typically build in a cushion of 15 minutes or so to improve their on-time statistics.
However, you could also arrive as late as 6:45 p.m. and still be considered on time in terms of how the FAA keeps on-time statistics.
And you could arrive later, even substantially later. It's one of the realities of flying. There are a number of reasons for such delays (often it's because of a delay earlier in the day at a different city that causes the aircraft to run late for the rest of the day). As a frequent flyer, if I arrive with less than an hour delay, I'm happy. This year, I've had very good luck with my flights. But in recent years, I've had delays of several hours on several occasions.
Personally, I would not book a nonrefundable event on my arrival day, especially not 2 hours and 35 minutes after the scheduled arrival -- when it would take over two hours to get from the gate to the destination in a best-case scenario and any delays with the flight, DME, and/or Disney Transportation could mean arriving at the event too late.
