Do not need to rush, while there are a lot of people, nowhere near as bad as some make it out to be,
It does not open till 9 am and you will be waiting outside, then waiting inside.
The sign of 100 applications per day is still up and Jim also said the same,
As long as you do not go on Monday or first day after some holiday, then its not a problem,
You can cheat a little to jump the queue if you dare. Ask to go to the toilet, entrance to the toilet from the side, but once inside, you really do not need to return to the queue, can just walk over and join the queue to the window.
Number that they give you is NOT number to follow, you queue up, Number is to collect your passport.
Its really not a difficult process as long as you have all the required paperwork, there is even a guy outside with Toyota Avanza that does photocopy from the back of the car(no idea on the costs)
And if you do not have required paperwork, i do not think agents will be able to help anyway.
One tip i heard from others and Jim, if returning by bus , when you entering Thailand, to put 200 baht in your passport for Thai immigration if you do not have 20 000 baht cash to show.