From memory no kids are allowed until Friday afternoon
Web site says "Trade Exhibition" and then "Public Airshow" with a one day overlap on the 1st and the public only allowed in after 2.00pm.
Usually at about 12pm Friday the exhibitors in the trade halls have packed up and are racing for the exits before Mum, Dad and the kids from Corio come through the doors. By 2:15pm anything free like pens and stickers are all exhausted and you'll not get near a flight simulator in the hall or a Steyr or Minimi at the Army recruitment tent.
Tuesday - Friday are the best days for the pro's.