For me processing time was 7 days total. I provided last 3 months bank account statement in Finnish from "OP pankki". They did request additional documents 1) flight ticket from Finland to Thailand, 2) latest payslip and 3) certificate of employment in English (I originally provided "väliaikainen työtodistus" in Finnish). Visa start date was the visa approval date, not my arrival date.
Do I need to prove 500k THB savings only when applying at embassy and doing extension at immigration, or also when entering Thailand (and getting a new 180d stamp)?