Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Kuala Lumpur to Douala as you normally would.
For a flight from Kuala Lumpur to Douala, you will be flying into Douala. Douala (DLA) is just 4.1 km from the centre vof the city. Douala is the only Douala airport and it handles 0 inbound flights from Kuala Lumpur per day. 1 airline has flights to Douala from Kuala Lumpur on a regular basis.