Flight Sydney Airport departs from Sydney Sydney Airport at 10:05 and arrives at Brisbane Brisbane Airport at 11:35.
The flighttime is about 1h 30m. The distance travelled ("as the bird flies"): 680 Km. So the average speed is roughly 453 Km.
The best day to arrive at Sydney is Monday and it would be best to avoid Wednesday, as prices are on average 301.96% higher than on Monday. (Average prices, based on 2637358 datapoints.)
We have a lot more statistics for flights QF 512 and between Sydney and Brisbane.