Dhaka – Guangzhou Oct.15th, 2009 (Thursday)
There are no direct flights on this day, but only conjoint flights with transfers at Singapore or Kuala Lumpur are available. Transferring at Singapore will take shorter flight time, and here is the flight schedule for your reference:
Dhaka – Singapore SQ435 0055/0555, Singapore Airlines
Singapore – Guangzhou CZ352 0800/1150, China Southern Airlines

Guangzhou - Dhaka Oct.25th, 2009
One direct flight is available, flight schedule: CZ391, 2200/0025, China Southern Airlines

Besides, taking direct flights will cheaper than taking conjoint flights. And from Dhaka to Guangzhou, one direct flight is available on Mondays, Wednesdays, and Fridays. So, personally you can choose to go to Guangzhou on Oct.16th (Friday), in that case you can take the direct flight. For the price, you can consult the airlines or some local booking agencies.