@Mookie ***
I did it in Jomtien/Pattaya. I needed to have at least 15 days left on my "exempt visa entry" to apply for a "90 day Non O visa". With all the requirements : 50 years, 800k on Thai Bank account for at least 2 months before application and proof of residency. In case you don't have enough days left on your "exempt visa entry", you can first make one extension of 30 days (1'900.B), giving you the time you need.