I'm from Australia and from the guys in the know here their advice goes in this order.
Get your Non-O visa in your home country.
When you land in Thailand you have two weeks to open a Thai bank account and deposit the
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0 Thai Baht and leave it there to marinate.
You can start at the same time to do the
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Thai baht per month income thing into that account as well and use that to pay your bills etc but must make sure there are no breaks in those payments.
Get your paperwork in order for your first 12 month extension the word on the street is to get your passbook stamped by the bank to verify your
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0 in your account is the same day as your applying for your extension at immigration.
When your second 12 month extension comes up for renewal you can now use the
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Thai baht income as proof once that extension is granted you can then technically take the
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0 Thai Baht out and keep using the
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0 Baht income as proof from then on.
I'm happy to be corrected if I got it wrong?