Flight Changi Airport departs from Singapore Changi Airport at 19:40 and arrives at Hong Kong Hong Kong International Airport at 23:35.
The flighttime is about 3h 55m. The distance travelled ("as the bird flies"): 1322 Km. So the average speed is roughly 338 Km.
The best day to arrive at Singapore is Thursday and it would be best to avoid Monday, as prices are on average 180% higher than on Thursday. (Average prices, based on 2263742 datapoints.)
We have a lot more statistics for flights TR 974 and between Singapore and Hong Kong.