Can I extend my one-year Non-O retirement visa by one month, and how does the 90-day report work?

Q. can I do a one month extension on a one year non O retirement visa ?

-> No, there is no 30 days extension on Non-immigrant based visa/extension. What you can do is applying for an extension by meeting all requirements for 1-year extension, and try to ask for shorter validity.

Q. how long before it expires

-> You can apply for an extension within the last 30 days of your current stamp at most immigration offices.

Q. do I have to do it at the same time or is it ok when I just go for the extension ?

-> That depends on your current stamp. Go to the office to apply for an extension and ask when is your next 90-day report.

Q. I mean do I have to mention the 90 days?

-> as above, check with your local office.