Can only do after 14 days before 90th date and 7 before. Also, if you have new passport, the first 90 day report with that passport must be done I person. At least was like that for me 3yrs ago.
I just renewed my non-o retirement extension on Thursday . They carefully checked bankbook for previous 12mo for the 800k/400k balance. And gave paper with date to report in 3mo again. So, answer is solid yes.
I tried 3 yrs ago 40 days before but was asked to come back when expiry is within 30 days. My reason was to go to dissertation session of my sister, that was not acceptable so I missed it. They might do if some very special reasons, but the only way to know whether they think is good enough reason is to go and ask.
I had to go pattaya immigration to do 90 day in person yesterday as had new passport and online did not work due to that. Not a word about tm30. Did not have anything in New passport about tm30 either as done online before when old passport in use still.
Just go to immigration and apply extension of stay for 30 days. Simple. More than that u can not get during normal circumstances without leaving the country. Whether can get another extension under coming extraordinary circumstances remains to be seen