How far in advance can we apply for an extension of our Non-O Retired Visa, and how old can our documents be for immigration acceptance?

Why take the effort to respond when OP has been answered on another page, he is trolling

You have already been provided with a response on another site. Accordingly, the Hua Hin Immigration Office accepts applications up to 45 days prior to the expiry of your current permission to stay.

Should the application be submitted with 30 days or less remaining on the current permission, you may be assured that both the income certification issued by the embassy and the extract from the Amphur confirming the marriage will be deemed valid and accepted by the immigration.