Should I apply for a 1 month extension or do a border run before applying for a Non-O retirement visa in Thailand?

Okay what this topic isn't gonna turn into is a "can I open an account on xxx entry stamp or visa?

@Tony ******

you misunderstand how the process works

You don't need to have the 800K baht seasoned for 2 months to apply for the initial 90 day Non-O visa at the immigration office in Phuket. You just need to have the funds transferred into a thai bank account of yours on the day you apply for the 90 day Non-O visa.

You DO need a minimum of 15 days left on your current stamp to apply for that visa at the Phuket immigration office because the application goes under review for 2 weeks before you go back to get the Non-O visa and new 90 day stamp inked in

The 2 months seasoning is only when you go to apply for the year extension AFTER you got the 90 day Non-O and let the stamp run down until you have 30 days or less left on it

SO

work on the account, get it open, get the funds in it, and go apply for the initial 90 day Non-O visa for 2000baht at the Phuket Immigration office.

If you need to take the 30 day extension so you have the minimum 15 days you need to apply for the Non-O visa, take it

You may have issues opening a bank account, not easy these days on a short term visa

Far Far easier to get a Non-O before you arrive, trying to open a bank account (without an agent, who will only do it if you also do the visa/extension with them), on a visa exempt is like trying to push treacle uphill.