Usually the 60 days tourist visa can be prolonged for another month as I know. How early before the 60th day can I come to the immigration office? Usually, 2 weeks is the recommended time, but can I come earlier, for example?
TLDR : Answer Summary
You can apply for an extension of stay for your 60-day tourist visa up to 30 days before the visa expires, according to the immigration rules. Some offices may allow you to start the application 45 days before expiration, while busy locations like Pattaya and Koh Samui may have more restrictive timelines, possibly limiting applications to the last 7 days before expiration. In Bangkok, it is possible to receive your extension on the same day you apply.