Install gshutdown by entering the following commands in the terminal:
sudo apt update sudo apt install gshutdown
Description:
Graphical shutdown utility and shutdown timer
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. . The graphical user interface uses Gtk+2.
Homepage: http://gshutdown.tuxfamily.org/
Version: 0.2-0ubuntu9
Section: universe/gnome