As for the way Kings Island does it, as I worked Diamondback and often was at co-dispatch (that green button near row 16), we were trained to not hit that button until the driver (yes Driver beep beep!!) gave the all clear. I'm pretty sure the button being pressed down on (HTCO can clear this up for me as he worked at Diamondback more recent than I have) doesn't let the panel know the button is pressed. The driver's dispatch buttons and the co-dispatch has to be pressed at the same time or within 3-5 seconds (can't remember) in order to dispatch the train or the ride would set up. It didn't work as the "thumbs up" for the clear....we had to get the clear from the station floor, give the high clear and announce clear so the driver (yes, beep beep ) would know we were ready to dispatch to give the all clear.
At Diamondback, there is a 7 second time out, and the panel does have an idicator light as to when the co-dispatch button is pressed. And you are correcet, you're supposed to wait to hit the button until everyone including the driver has given the clear.