Usually it opens 7.30am ish, with cars arriving as late as 10am, obviously the later you arrive the less chance of getting a park in the main display area or having your car judged.
Trophies are usually just after lunch with the event wrapping up mid to late afternoon
The pony round up gets quite a turn out of cars, if the weather is good expect it to be busy, cars come from Bathurst, central coast, port Macquarie as well as local Sydney vehicles.
Well worth visiting if you have nothing planned.