GShutdown is a utility which allows you to schedule the shutdown or restart of your computer. With it you can simply and quickly choose the turn off time at either a specific time or after a countdown.
* Compatible with GNOME, KDE and XFCE.
* Compatible with GDM and KDM to shutdown, reboot or close the current session, without being root.
* The ability to choose a command to stop the computer (like “sudo poweroff”, for example)
* Systray icon
* Visual notifications (to warn the user that his computer is going to be stopped in a few seconds !)
* Three different ways to schedule the turn off time : « at time and date », « after a delay », « now ».
Install Gshutdown

Use this command in terminal:

sudo apt-get install gshutdown

Or,type “gshutdown” to search in Applications->Ubuntu Software Center and click to install.

Gshutdown can be open from Applications->Accessories->Gshutdown