Flight Brisbane Airport departs from Brisbane Brisbane Airport at 06:15 and arrives at Melbourne Melbourne Airport at 09:40.
The flighttime is about 3h 25m. The distance travelled ("as the bird flies"): 1343 Km. So the average speed is roughly 393 Km.
The best day to arrive at Brisbane is Saturday and it would be best to avoid Monday, as prices are on average 161.1% higher than on Saturday. (Average prices, based on 1154101 datapoints.)
We have a lot more statistics for flights QF 609 and between Brisbane and Melbourne.