When should I apply for a Non-O visa for retirement in Thailand before moving?

Personally come here, find an agent and get everything done here.

Try ringing a Thai Embassy or look at their website.

From the horse's mouth is best.

Not difficult!

I think there may be some confusion about the visa types. The Non-OA is a 1-year visa and usually requires health insurance, a medical certificate, and a police background check.

The Non-O, on the other hand, is initially issued for 90 days. After arriving in Thailand, you can open a Thai bank account, deposit the required 800,000 baht, and after the funds have been in the account for 2 months, apply for a 1-year extension.

Both are valid options depending on your situation, but the Non-O route tends to be the more commonly used one.

You want the Non Immigrant O visa, it's valid for 90 days, so you can apply within 90 days of your relocation

Apply for a Non-O

Sounds like you should be applying for the 90 day Non-O not the Non-OA which is a 12 month visa. A Non-O is valid for 90 days from the date of issue (you must enter Thailand within those 90 days and get a 90 day entry stamp) so apply about 6 weeks before you travel.

I'm not sure you have the type of visa you want to apply for correct.

The Non-OA visa is a 12 month visa that requires insurance, a medical certificate and a police check.

The Non-O visa is a 90 day visa that requires you to open a bank account once you arrive in Thailand, deposit a minimum of 800k baht which must season for 2 months before you apply for a 12 month extension of stay.

Which one you choose is up to you but the Non-O is the most popular by a long way