Flight Changi Airport departs from Singapore Changi Airport at 07:50 and arrives at Xiamen Gaoqi International Airport at 12:25.
The flighttime is about 4h 35m. The distance travelled ("as the bird flies"): 1797 Km. So the average speed is roughly 392 Km.
The best day to arrive at Singapore is Wednesday and it would be best to avoid Sunday, as prices are on average 78.51% higher than on Wednesday. (Average prices, based on 126671 datapoints.)
We have a lot more statistics for flights SQ 868 and between Singapore and Xiamen.