A few weeks if I recall. You can upload the current statement with a brief note attached explaining the timeline and when you'd be able to upload the most recent up to date statement. Did you not already upload a statement with your application submission?
don't complicate it, as John said go to the office and ask if they will convert visa exempt to non O, if yes bounce out to Cambodia and back on visa exempt (don't use Poipet crossing) then go to your local office with bank statement and buy a non O based on being over 50. 2 months after that apply for the extension.
the other day the government signalled repealing or suspending this tax law to stimulate the economy. Nothing is written in stone as far as this tax since 2024, everything is on the table.
Include a simple brief cover letter detailing your work. Any company documents you have. A contract stating you can work remotely in Thailand and that you won't conduct any business with Thai entities.