ANA (All Nippon Airways) offers multiple check-in options to accommodate passengers' preferences and schedules. The earliest you can check in depends on the method you choose and your departure location.

Online and Mobile Check-In: ANA provides online check-in services from 24 hours up to 75 minutes before your scheduled departure time for international flights and up to 20 minutes before departure for domestic flights within Japan. To check in online, visit the ANA website or use the mobile app, enter your booking reference and surname, and follow the prompts. During online check-in, you can enter your passport details, choose or change your seat, and receive your boarding pass electronically. If you're traveling with just hand luggage, online check-in allows you to head straight to the security area or boarding gate after arriving at the airport. If you have checked baggage, you’ll need to go to the baggage drop-off counter at least 60 minutes before departure for international flights and at least 20–30 minutes before for domestic flights. 

Airport Check-In: If you prefer to check in at the airport, ANA provides staffed check-in counters at major airports. It is recommended to arrive at the airport at least 2 hours before departure for international flights and 1 hour before departure for domestic flights to allow sufficient time for check-in, security checks, and boarding. Please note that check-in counters typically close 60 minutes before departure for international flights and 30–40 minutes before departure for domestic flights.

Self-Service Kiosks: ANA offers self-service check-in kiosks at select airports. These kiosks allow you to check in, select seats, and print your boarding pass. Kiosk check-in is available from 3 hours to 1 hour before departure for international flights, depending on the airport. For domestic flights, kiosk check-in is available from 2 hours to 30 minutes before departure. 

Special Considerations: Passengers requiring special assistance, traveling with infants, unaccompanied minors, or pets, or those with non-machine-readable passports or visas may need to check in at the airport counter regardless of the check-in method. It's advisable to verify your eligibility for online check-in based on your specific circumstances.

Conclusion: While ANA offers online check-in starting 24 hours before departure, it's essential to verify your eligibility based on your specific flight details and circumstances. Always check the airline's official website for the most current information and guidelines. If in doubt, contacting ANA directly can provide clarification and assistance.