To Send a Scheduled message on Samsung Galaxy Device, do as follows. It sends the Messages at the specific later time
1. Open "Messaging" app
2. Tap on "Create New", write your message and assign the receiver contact
3. Tap on "Menu button" and choose "Scheduled message"
4. Specify the Time and Date
If your phone doesn't support "Scheduled Message" feature by default, or the feature has been removed after a system update, read this Android tip:
How to Send Scheduled Text Message on Android
Which works perfect on almost any Android device.