Flight Changi Airport departs from Singapore Changi Airport at 05:15 and arrives at Guangzhou Guangzhou Baiyun International Airport at 09:25.
The flighttime is about 4h 10m. The distance travelled ("as the bird flies"): 1282 Km. So the average speed is roughly 308 Km.
The best day to arrive at Singapore is Monday and it would be best to avoid Wednesday, as prices are on average 312.9% higher than on Monday. (Average prices, based on 307124 datapoints.)
We have a lot more statistics for flights TR 100 and between Singapore and Guangzhou.