Regarding the 30 Day Extension on a Tourist Visa, two questions:
1) How early do you NEED to apply prior to your initial Tourist Visa ending?
2) How early CAN you apply prior to your initial Tourist Visa ending?
Thank you
TLDR : Answer Summary
You can apply for a 30 Day Extension on a Tourist Visa right up until your current stamp's expiry date. However, the earliest you can apply varies by location; some offices allow applications with 45 days or less remaining on your visa, while most allow applications with 30 days or less. A few offices, like those in Jomtien, may only permit applications when there is one week or less remaining.