Flight Sydney Airport departs from Sydney Sydney Airport at 16:35 and arrives at Brisbane Brisbane Airport at 17:05.
The flighttime is about 0h 30m. The distance travelled ("as the bird flies"): 680 Km. So the average speed is roughly 1360 Km.
The best day to arrive at Sydney is Saturday and it would be best to avoid Thursday, as prices are on average 81.24% higher than on Saturday. (Average prices, based on 2636403 datapoints.)
We have a lot more statistics for flights QF 538 and between Sydney and Brisbane.