One more tip: The first thing you encounter is the "Over the Road" show. This includes the Revival Car Show for pre-73 cars; Bonhams Auction; trade stands; the funfair, with helter skelter (useful for getting a view!) and "Wall of Death"; and varied food stalls.
Last year on another forum a gentleman from Belgium reported that he had a most enjoyable time there; in mid-afternoon he became curious about the stream of people crossing the footbridge and only then discovered that he'd spent the greatest part of the day in the car-park and had just a few hours left for the Revival itself!
Tempting as it is to linger, get into the main site while it is still quiet. The outside attractions remain open into the evening so save them for the trip back to your car.
I see Friday tickets are now also sold out this morning so hopefully everyone got them who wanted them.
~iw