@Pete ******
Yes you enter visa exempt and when you have 30 days left (some offices allow 45 days) you apply to convert to a Non O at your local immigration office. Cost is 2,000 baht.
You do need to have the 800k in a Thai bank in your name only to do so.
That will give you a 90 day visa and when that’s running down you apply for the year extension.
For the second and subsequent years you can switch to the 65k transfers method.