Screen Time is a new function in IOS 12.
In the Screen Time under settings, you can set scheduled Downtime to restrict your son from using apps outside of those that have been allowed with App Limits, you can set specific time limits on app categories like social networking or games, and you can access Content & Privacy Restrictions. When settings this up, please make sure not to block apps during the day.
Using Downtime from 9:00pm-8:00am during weekdays is the easiest configuration. You can use App Limits on Weekends as you see fit.
For an alternative monitoring system, you can verify if your Internet Router has a Parental Control systems built-in or purchase a Disney Circle or the new Circle Plus to add to your home network. This allows you to monitor any device and see usage as well as block sites without having to access your son's iPad.
Another option suggested by Matthew Nadler and Susan Klein is to use OpenDNS, a Cisco service, that offers free content filtering. We use it to block gaming sites, but they have a full range of filters like adult sites, chat rooms, and alcohol/drugs. The setting are effective for any device in the home.
Click here to see the sign-up page with more information.
The only tricky part is making a change to your internet router settings to specify Cisco's Domain Name Servers (DNS) instead of the one used by your ISP.
Cisco's instruction page is here.
Finally, you will want to install a helper application that updates your settings when your ISP changes your dynamic home IP address. This happens periodically unless you're paying a premium for a Static IP address.
The helper app instructions are here.
We have found this service effective and helpful. You can email us with any questions.