no need to have consistent amounts. Only the closing balance should be 500k minimum. It's better if you can prove the source of transfer in amount added before application. In my case, I showed them my salary payment slips for the last six months.
not bad. They checked the documents I provided carefully and demanded more detailed financial statements to submit. I had to fulfill them. Especially they wanted to see many payments transactions in my bank statement of last past six months.
Update: I didn't get mail from the embassy till this morning. So I went there in person to ask the status. They told me to wait till next week to know my result and it's their regular processing time for DTV they said. I applied on Wednesday and didn't get it back till this Friday. So above mentioned DTV processing time 1-3 working days is not true for Hanoi.