Is there a limit on how much of the 800,000 THB can be used during the visa extension time frame?

The rules for the banked money method for a retirement extension state you need to have the 800K baht in a thai bank account in your name only for 2 months before you apply for your extension, you need to keep the 800K in the account for 3 months after the extension is granted and then the balance can't go below 400K for the rest of the year.