If you open the Control Centre in the System Tray it has a list of Scheduled Tasks and it is probably in there I would guess

It says the following in Help -

"Schedule Daily Test

Use this dialog to run the Complete test at regular intervals.

The Scheduled time group allows you to activate daily testing and determine at what time the test is to be launched.
Select the If missed option to ensure that, in case the test is not performed at the defined time (e.g. the computer is turned off), the test will be launched immediately after the computer is next started.
In the Schedule group, Complete Test is selected (as the scheduled test). The User Test option is available only in AVG Professional Edition.

Click the OK button to save any changes and close the dialog.
Click the Cancel button to close the dialog without saving any changes."