Taifun
2
It might be possible, but before trying it, we will not be 100% sure...
I would use the alarmmanager extension App Inventor Extensions: Alarm Manager | Pura Vida Apps to trigger something at a given tine together with the itoo extension to call the Vibrate method of the Sound component
http://ai2.appinventor.mit.edu/reference/components/media.html#Sound
Taifun