If it was only 8 minutes, the jets wouldn’t have had time to get there. In any case, there’s no “wheel.”
He just set the controls for a descent, but how could he have done that? Normally there would be coordinates or a destination, I would think, unless there’s some way to put it totally under manual control and he set it to descend and simply sat back and kept clicking the lock on the door so the pilot couldn’t get in.
My understanding is that on an A320, if you push forward on the stick you can set a rate of descent and the autopilot will hold that rate of descent for you.
Descent took 18 minutes.