Send Later Messaging Finally Comes to Apple

An excerpt from 9to5MAC - 

Here’s how to schedule messages to Send Later in iOS 18

By Michael Potuck

Apple launched the Send Later feature for email with iOS 16. Now with iOS 18, we have the same functionality for Messages.

How to schedule messages to Send Later in iOS 18

Note: Send Later in Messages only works with iMessages, not SMS texts

1. Make sure you’re running iOS 18 on your iPhone
2. Open the Apple Messages app and select an existing text or create a new one
3. Write your text, but before hitting the send button, tap the + icon on the left side of the text field
4. Tap More (or swipe down), now choose Send Later
5. Pick a date and time to schedule the message
6. Tap the send button (up arrow) to set the scheduled message

After you set a scheduled message, it will show up on your screen in the thread with a dotted-line bubble.

Tap Edit if you’d like to change the scheduled date/time, want to send it now, or delete the scheduled message.

https://9to5mac.com/schedule-messages-send-later-ios-18/