Does Thai Airways have online check-in?

No, currently Thai Airways does not offer this service.

How much time should I allot at the airport for check-in?

For international travel, Thai Airways recommends you arrive at the airport at least 2 hours before your flight. Flights close 30 minutes before departure.

When do I need to be at the boarding gate?

Passengers traveling internationally should be at the gate 45 minutes before departure.