Can I extend my 3-month NON-B visa to a yearly one more than 7 days before the expiration date?

Yes, you can apply for an extension of your 3-month NON-B visa more than 7 days before its expiration. Generally, you are allowed to apply for an extension when you have 30 days or less remaining on your current visa. In Bangkok and Chiang Mai, you can apply up to 45 days in advance. Importantly, any time you apply early does not get deducted from your new extension; the year is added to the expiration date of your current stamp.