I converted my Thai driving license in Department of Land Transportation (Area 3), Sukhumvit.
I stayed in Thailand less than 90 days, no need to report 90 day report. But, need report TM30 and apply the residency certificate in Immigration Division 1 (Immigration Bureau). The residency certificate must be issued within 1 month when you apply the thai driving license.
It needs time for the foreigner to make the appointment day with transportation department and to prepare the residency certificate.