When the buses come by the electronic sign on the front will tell you where the bus is going. You shouldn't have to wait more than 10-15 minutes (probably less) to get a bus to your destination.
The trip from CSR to DTD is probably 10 minutes tops (the trick is how long you have to wait to be picked up).
If you have to be there by a certain time I would give yourself a half an hour to be safe, most likey you will be there much quicker.