You can set up a scheduled task/cron job to call a script on your domain automatically at a certain time/date by logging into Plesk and following the below steps:
Click on the Domains option in the left hand menu then click on your domain.
Click on the Scheduled Tasks icon on your Domain's page
Click on the user you want to run the task (generally the FTP/site user)
This page will display existing Scheduled tasks if any exist. Click on the Task name if you wish to edit an existing task or Create New Task if you want to create a new task.
The crontab page shows boxes for all required fields and follows the Linux cron job principles outlined here.
If you require any further help please submit an enquiry via the Namesco Online Control Panel.