As a rule, it depends on the airline. Information about the start of registration is traditionally indicated on each ticket. Check it out or contact the airline for the exact check-in time.
Most popular check-in arrival time:
Domestic flights: check-in at least one hour before departure.
International: Check-in at least 1.5 hours before departure.
Charter: Check-in desks open 2 hours before departure and close one hour before departure.
Do I need to register?
If you have already checked in at a special desk and you only have hand luggage, you can go straight to the screening.
If you have baggage that needs to be checked in, you can print your baggage tags from the check-in machines at the airport. Attach them to your luggage and drop them off at the counter marked “bagdrop”.