@Ruth ******
I did mine in roughly 4 weeks in Krabi. Certificate of residency is achievable with TM30 only (they were not really interested in rental agreement either). Then I did a 1 day course in local driving school for 4k THB, passed theoretical exam on the same day, then they told me I need to wait 2-3 weeks for appointment at DLt to get my license. That I did, paid another 150 THB or so and got my license.
Keep in mind that you probably can’t get a residency certificate in Krabi/CM for Bangkok rental, so you’d have to get a short term rental in one of the two places for that.