“Check-in time” refers to the time that the individual traveler is processed or “checked-in” by their air carrier. This process includes both issuing a boarding card AND tagging checked baggage. All passengers must have this process completed a minimum of 45 minutes before the flight.
The airlines “cut off” or close check-in 45 minutes before the flight and will not accept additional passengers for that flight. Once checked in, passengers should proceed immediately to security screening.