He encontrado esto:
"You can also set an alarm to wake up to, and the Mi Band will buzz at the appropriate time. An early bird alarm is also available and will wake you 30 minutes before your preset time if the band detects that it's the best time to wake you up."
O sea que puede que sí que haga lo que tú quieres. De todas formas, si te lo confirma algún forero que la tenga, mejor.