Am I correct that resorts buses to MK don't start to run until 1 hr. before extra magic hours start up?

[TigerLaw]

If that is wrong, what is the correct time?

 

[SteveH]

The official Disney statement is generally operate from 45 minutes before a theme park’s opening

 

[CarolynFH]

If that is wrong, what is the correct time?

Notwithstanding the statement on the Disney website, the buses start running about one hour before early opening. If you want to be on the first bus and near the front of the pack at the entrance to the park, it’s recommended that you be at the bus stop about 90 minutes before early opening time.