When should I visit the immigration office before my visa-exempt stay in Thailand expires, and can I opt for a 60-day extension instead of a 30-day one?

The best practice is to visit the immigration office about seven days before your visa exemption expires. Currently, you can apply for a 60-day extension as a COVID-19 measure only after first obtaining a 30-day extension. However, availability may vary by location, so it's essential to check with the local immigration office for specific procedures.