I set mine to automatically shut down at 12:00AM and boot up at 3:00PM everyday. If I want to shut it down earlier, I use a VNC client from my iPad or iPhone to remote control it.
The auto shut down and boot up time can be set in:
System Preferences->Energy Saver->Schedule.
The auto shut down and boot up time can be set in:
System Preferences->Energy Saver->Schedule.