When is the earliest I can apply for a tourist visa to Thailand if I plan to fly out on January 6th?

The earliest you can apply for a tourist visa to Thailand if you're planning to fly out on January 6th is generally advised to be around the beginning of October, as you can submit your application anytime now. The tourist visa is valid for 90 days from the date of issue, and you have 90 days to enter Thailand once it's issued. Some commenters suggest waiting a week or two due to bugs in the ThaiPass system, and there are concerns about overloading the application system, especially for those traveling soon.