How soon can I apply for a 30-day extension on a visa exempt entry in Thailand?

If you are in Thailand on a visa exempt entry with a 30-day stay, you can apply for an extension immediately, though it is generally recommended to apply about 5-6 days before your visa expires. However, some immigration offices, like in Jomtien, have specific rules requiring you to apply when you have 7 days or less remaining on your visa stamp. It's advisable to check the specific regulations at your local immigration office, as they can vary by location.