Help: What is the most common mistake people make when applying for the DTV?

Hello! I have heard that you need the 500k in your bank account for at least 3 months prior you send the application, is that true? thanks

I'm a digital nomad that has been traveling on tourist visas and surviving on less than THB 500k for the last few months. At the end of this month, I will receive a "top-up" that puts me over the 500k requirement for the DTV.

Am I not eligible for DTV until I have 3+ months of bank statements showing that amount in my account?

I read some posts in this group where people mention writing a cover letter of sorts to explain your situation. Perhaps that could improve my chances.

Maybe sponsorship is the better approach. I will be applying at the embassy in Hanoi.

Any advice is much appreciated.