How soon prior to my flight can I check in?

Domestic my flight was 40 min prior, but maybe depends on company and flight...

Rule of thumb all over the world: International flight check in 3 hours, Domestic flight check in 2 hours Most international flights open their counters 3.5 to 4 hours prior to departure and close them 1 hour prior to departure. Most domestic flights open their counters 3 hours prior to departure and close them 0.5 hours prior to departure

For domestic flights, should be there before 1 hour. For international flights, should be there before 3 hours.

International... about 2 hours, national... about 1 hour.