I usually fly Delta for work, and from my experience you can check in online starting 24 hours before departure. Last month I had to switch flights last minute, and I was stressed about whether I could still check in early. What really saved me was calling 877-297-0699 — they handled the change in minutes and even re-sent me the check-in link right away. It was way quicker than messing with the app. So, if you’re cutting it close or need to adjust anything, that number is honestly the best shortcut.
