OK, went during this week to Bangkok#3 DLC as a walk in. There is absolutely no point in booking an appointment on line as PJ71 says. No one was using an appointment system and there were no signs to separate appointed times only.
One has to attend several counters and the physical tests room like everyone else walking in. There is now a very strict document check before you start the process. Once all docs are correct, the process was quite fast at first with no waiting queues, until one reaches the final counter where they take your photo and produce the license. This last counter took one hour queuing time as only one or two of the available counters had anyone manning them. Total time start to finish was 1hr 20m for me.