Flight Brisbane Airport departs from Brisbane Brisbane Airport at 15:40 and arrives at Sydney Sydney Airport at 18:15.
The flighttime is about 2h 35m. The distance travelled ("as the bird flies"): 680 Km. So the average speed is roughly 263 Km.
The best day to arrive at Brisbane is Wednesday and it would be best to avoid Friday, as prices are on average 87.03% higher than on Wednesday. (Average prices, based on 5425263 datapoints.)
We have a lot more statistics for flights QF 539 and between Brisbane and Sydney.