The sooner you check in, the sooner you're able to pick your seat, if you haven't already. If you're flying on a basic economy ticket, this will be the first opportunity for you to select a seat. Seat selection is first-come, first-served, so it's important to check in as soon as it's allowed.

Checking in exactly 24 hours before your flight is one of the best ways to ensure a smoother travel day, primarily because it dictates your priority in several key areas. For airlines like Southwest, your check-in time determines your boarding group (A, B, or C); checking in at the T-minus 24-hour mark is the difference between an aisle seat and a middle seat in the back. For other carriers, checking in early allows you to snag the best remaining seat assignments or potentially "buy up" to premium economy at a discounted rate before others have the chance. Logistically, checking in early allows you to confirm your travel documents, pay for checked bags at a lower online rate, and receive real-time notifications about gate changes or delays. Furthermore, in the rare and unfortunate event of an "oversold" flight, airlines often use the time of check-in as a tie-breaker when deciding who gets bumped; those who checked in last are typically the first to be moved to a later flight. By securing your digital boarding pass a day early, you also save time at the airport, allowing you to head straight to security if you are not checking bags, thereby reducing your overall "airport stress" significantly.