Agreed that you want to arrive at the parking lot at least 30 mins before opening from the parks you mention. If you change plans and start at MK one morning I'd add another 15 minutes if you really want to be there at rope drop since you still have the TTC-MK leg.
When I've taken groups of friends/family I've started "indoctrinating" them about the advantages of arriving for opening quite awhile before the trip. Then when we'd get to Orlando I would joke with them that they were about to see the Disney Nazi in action but that they would likely get more done before 11 am than the whole rest of the day. If I was their ride to the parks I would good naturedly insist that we stick to the departure time while promising a rest in the afternoon.
(we would return to our condo and/or chill in one of the monorail resorts for awhile) If they had their own transportation and really did not want to leave so early we'd meet later in the parks. It's worked pretty well most of the time although one trip I felt sad for some younger kids whose parents would not get up and take them early. They had to stand in a long line for everything. Finally the last day the parents let the grandparents take the boys early and happily they left with a better memory of the MK.
Many of our first timers seemed sceptical it was necessary to be there at rope drop but once they got there and saw the difference in the crowds as the day progressed, they were up early every day.