I usually plan on leaving for the airport 3 hours before the flight, with a rental car. It usually seems extreme and we end up sitting around, but I'd rather have that than missing our flight.
When we used a car service, it was 2 hours before our flight.
But I have seen monster lines at security at MCO as well. Last summer, they hardly had any lines open the day we were there and it was a total zoo - never saw anything like it before there.