The first extension had that requirement. (800k for 3 months and 400k for the rest of the year). If you don’t meet with those requirements then you’ve broken the chain of what you committed to do. Regardless of any future requirements for a further extension.
For the first extension you agreed to keep the 800k for 3 months after the extension was approved. That amount couldn’t drop below 400k for the rest of the year.
So a partial withdrawal of 400k is possible 3 months down the line.
However if you don’t top it back up to 800k two months before your second extension application then you are leaving yourself no option other than having 12 perfectly timed monthly transfers of 65k+ showing as international transfers.
If you had the 800k you could use that as a backup if for some reason something went awry with one or more of the transfers.
If successful with the second application using transfers then you do not need to keep any money in the account for any length of time. If it comes in it can go out same day.
You no longer have the option of a sticker in your passport for a visa these days as all embassies are on-line only now. Print the PDF as that is your visa.