In this article I'll show You how to do that.
Open Ubuntu Software Center, go to Edit -> Software Sources... and then to Updates tab. Where it says Automatically check for updates, choose Never.
By this way, you'll prevent Software Updater from automatically launching and checking for available updates. Instead, this job depends on You. By the way, notification will be displayed immediatelly when security updates are available.
From now, You and only You will update Your system. You can do this through Software Updater or Terminal, it's Your choice.
Software UpdaterJust press meta key (usually Windows logo key) and type update. Open Software Updater and wait to check for available updates. If there are any, click Install button and wait to finish installation.
TerminalOpen terminal and:
sudo apt-get update && sudo apt-get upgrade
If there are any available updates, confirm the process (type Y when prompted), and wait to finish installation.
After update process, restarting computer is probably the best and the safest step.