I talked to the "great Thai helper" there two weeks ago and he said to come last week August. so had been following that time frame. But he said that without seeing anything so guess I'll get everything together now and go next week...
I provided no documentation other than my passport, an income statutory declaration, and a completed form when I received the current extension of stay via a "visa agent" from the chonburi office.
There was no school involved as my ED visa was granted for the purposes of obtaining scuba diving certifications.