What you can do right now
Open the booking confirmation and find the manage booking section. Try the date change tool once. If it fails or the price looks wrong, switch to phone or online chat immediately. Have the booking reference, passenger names and the preferred new date ready. Call or write while there is still time today, because tomorrow morning the options will be even fewer.

Available options
First option is a same-day or next-day change on the original airline. This keeps everything on one ticket when it works. You pay the change fee plus any fare difference. Travel time stays similar to the original plan.

Second option is to cancel the ticket and buy a new one on a different flight or even a different carrier. This only makes sense when the change fees are higher than a fresh ticket. You lose most of the original fare on basic tickets but keep the taxes in many cases.

Third option is to keep the original flight and adjust everything else around it. Change the hotel, shift meetings, or move the ground transport. This costs nothing extra on the ticket itself and removes the risk of higher change fees.

Risks
Waiting until tomorrow morning almost always reduces the available seats and raises the price. Online tools can show incorrect fees or freeze completely at short notice. If you cancel without checking the refundable amount first, you may lose more money than necessary. Phone queues get longer as the day goes on.

The fastest choice
If the online tool works and the extra cost is acceptable, take the change immediately. If the tool fails or the price is too high, call the airline now and ask for the cheapest available alternative on the same day or the day after. Keep the original flight only if the change fees clearly exceed the cost of adjusting the rest of the trip. Act while it is still today.

Summary
A flight tomorrow can still be changed, but the window is narrow. Try the online tool once, then move to phone or chat without delay. Compare a paid change, a cancel-and-rebook path, and the option of keeping the original flight. The fastest and usually safest move is to secure any acceptable new seat today rather than waiting until morning.