What are the procedures for 90-day reporting and converting a Non-O visa to a retirement visa in Thailand?

Let's clear terminology first. Once you apply for the initial Non-O visa based on retirement, it gives you 90-day entry (or initial admitted to stay) stamp. After that, you will apply for a 1-year extension of stay based on retirement/being over 50, <- this is not a visa anymore, it is an extension.

Q. 1 When is the fastest date can do the 90 days report before it expire?

-> If you know the due date, 15 days before is the earliest day you can submit a 90-day report online or in person at the local immigration office. (The last day you can do a 90-day report without any issue is 7 days before the due date for online reporting, 7 days AFTER for reporting in person. )

Q2 When is the fastest date can change the 90 days non o visa (before it expire) to 1 year retirement visa?

-> You cannot change 90 days Non-O visa to a "1-year retirement visa". You can apply for a 1-year extension based on retirement instead. Some offices including Bangkok, Chiang Mai, Phuket, and some others accept a 1-year extension when your current stamp remains 45 days or less. Other offices let you apply for a 1-year extension when it's 30 days or less.

Q3 For getting the retirement visa, should fill it which form?

-> Application form is TM7, and there are some more forms you have to fill out depending the office you use.

Q4 Any requirement difference between applying 90 days non o visa and 1 year retirement visa?

-> Differences may depend on where you applied for an initial visa and where you will apply for a 1-year extension. Anyway, you need to go to your local immigration office to get the latest handout for requirements for an extension based on retirement.

Here is general information for a 1-year extension based on retirement. Your office may have its own requirements. you need to get their specific version.