Can I Extend My Non O-A Visa Based on Marriage Instead of Retirement?

Hello. :)

Please advise:

when a non O-A visa (not an extension) is nearly expired, is it possible to apply for an extension based on being married to a Thai ( non O) instead of based on retirement (non O-A). As for the financial requirement--- 400k Baht seasoned for 2 or 3 months(?), is that 2 or 3 months up to the expiry date of the current visa (non O-A) or the date of application?

Last but not least, how soon can an application be done before the expiry date of the current visa?

Many thanks in advance. Be safe and healthy everyone :)