Yes closing balance of minimum 500k every month for last 3 months. I recommend you do this or wait & apply. Unless you want to experiment with THB 10k & more importantly wait and be anxious. The more you follow the rules clearly the better the chances.
Please take 1 year minimum. I have had rejection with 6 months all paid for classes & they gave me an ED Visa for 3 months & told me i can extend for another 3 months if needed. Quite a bummer unfortunately 😑