I have a early morning flight at 7:05 on a Friday in August in Bangkok. It is a domestic flight. What time would I need to be at the airport before my flight. I have hotel next to the airport.

What about Chiang mai airport? What is the check in time for domestic flights?

domestic flight check-in - 1hour prior to departure.

You should really check with the airline.

For TG, all flights (domestic and international) their website says:

Suvarnabhumi Airport

Departure and Check-in

Check-in counters open 3 hours and close 40 minutes before departure time

Boarding gates open 1.15 hours and close 10 minutes before departure time

You do have to clear security (after check-in), and those lines can be long as are the check-in lines (at certain times of day), and may have a long walk to your gate in the A concourse, so maybe give yourself some extra time.

Indeed you must check with the airline as AirAsia are more restrictive than Thai. This from their website.

"AirAsia (AK, FD and QZ Flights)

Our check-in counters are open two (2) hours and close forty-five (45) minutes prior to the scheduled flight departure time . Please produce the booking number/printed itinerary upon check-in together with your identification card or passport. Failure to present yourself at the counter before counter closure will result in denial for check-in."

I also recall they close the gates 30 minutes before departure; maybe someone can confirm this.

Indeed you must check with the airline as AirAsia are more restrictive than Thai. This from their website.

"AirAsia (AK, FD and QZ Flights)

Our check-in counters are open two (2) hours and close forty-five (45) minutes prior to the scheduled flight departure time . Please produce the booking number/printed itinerary upon check-in together with your identification card or passport. Failure to present yourself at the counter before counter closure will result in denial for check-in."

I also recall they close the gates 30 minutes before departure; maybe someone can confirm this.

This sounds like an airline policy, less the airport's {per say}. But also consider the source. Most carriers differ in policies and whatnot - be it a domestic or international destination.