Immigration offices in Thailand are notorious for their long queues, especially for tourist visas, education visas, and business visas. It can easily take you the whole day for a simple tourist visa extension. This is one of the main reasons many people decide to use a visa agency: to simply reduce the queuing time.
The best time to go to the immigration office is early in morning. Although it opens at 8:30 AM, you should be there around one hour before it opens. And you should still see a busy queue there already. Make sure you have the visa form completely filled out and documents ready.
