How to set up scheduled text messaging on iPhone?

This cannot be done on iPhones without jailbreak, only jailbroken phones can.

If the iPhone has been jailbroken:

Search for biteSMS in Cydia and install it.

1. In the SMS content interface, long press the SMS content and select "Forward" in the pop-up menu.

2. The recipient fills in the mobile phone number, clicks the "+" sign on the left side of the input box, a menu pops up, selects the clock symbol, and sets the time.

3. Click "Finish" after setting the sending time.

You can go to the App Store to download a "SMS Timer". There are many similar software.