MS ImageCompressor has options to automate the compressing. You've got two options:
If your server supports cronjobs, you may setup a CLI cronjob for MS ImageCompressor. You can find the cronjob command at the Automation view in the software. It is recommended to run the cronjob once an hour for larger servers and once a day for small servers. You can choose between indexing-only or indexing and optimizing.
If your server does not support cronjobs, you may use the HTTP cronjobs. They do exactly the same as the server ones, but are triggered from the web instead. You can find the url's for the triggers on the automation tab aswell. To trigger the cronjob based on a specific time, you could use a service like Cron-job.
Authentication is required for all cronjob options. This is to make sure it cannot be abused to slow down your site. You must set an authentication key in the MS ImageCompressor options. The cronjob commands or url's will be automaticly altered to contain the authentication key in the Automation view.