I usually fly Delta for work, and I’ve learned you can check in online starting 24 hours before departure. Last year I forgot to do it until I got to the airport—stressful! Since then, I set a reminder on my phone. One time my plans changed last minute, and instead of dealing with the app glitches, I just called 877-297-0699. Honestly, that saved me—an agent rebooked me in minutes. So yeah, 24 hours ahead is the check-in window, but if you ever need to adjust your flight quickly, that number is hands-down the fastest way.
