From in your Defense.com account, click on the Prevention icon in the navigation menu.

From the expanded menu select Vulnerability Scanning.

Click Add schedule (Calendar icon) and the Add schedule pop-up will appear.

Click into the Start date box and the calendar will be displayed where you need to select the date and time the scan is to run. Click off of the calendar to return to the Add Schedule box.

Select the Frequency you'd like the scan to run by selecting Weekly or Monthly and entering how often you'd like the scan to run by entering the number of weeks/months in the Every box. Ensure the Enable Schedule box is checked and click the Add Schedule button.

You've now added a scheduled vulnerability scan in Defense.com. You'll see the date and time of the next scan shown.