How to send "delayed" sms? Instead of sending an SMS right now, I would like to send a "delayed" SMS. For example, delay it by 45 minutes, or 60 minutes, etc.

Is there any way to do it?

I have tried the apps txtot, FutureText, and SMS Scheduler, but they don't work. The default iPhone "Messages" app cannot receive SMSes sent by these apps.
Without jailbreak what you ask isn't possible. Third party Apps from the App Store can't access the SMS service. 

With a jailbreak there seems to be apps on the Cydia Store that have this function. Like Future SMS.