Flight Changi Airport departs from Singapore Changi Airport at 21:00 and arrives at Sydney Sydney Airport at 06:55.
The flighttime is about 7h 55m. The distance travelled ("as the bird flies"): 5577 Km. So the average speed is roughly 704 Km.
There is an 2 hour time difference between Singapore and Sydney
The best day to arrive at Singapore is Tuesday and it would be best to avoid Sunday, as prices are on average 56.13% higher than on Tuesday. (Average prices, based on 399159 datapoints.)
We have a lot more statistics for flights QF 82 and between Singapore and Sydney.