Sync Duration

Dean_Gross The answer is: it depends  Obviously, the client needs to be enrolled first. As explained in the Enable co-management for existing Configuration Manager clients tutorial:

Starting in version 1806, automatic enrollment isn't immediate for all clients. This behavior helps enrollment scale better for large environments. Configuration Manager randomizes enrollment based on the number of clients. For example, if your environment has 100,000 clients, when you enable this setting, enrollment occurs over several days.

Check the CoManagementHandler.log file on the client for any errors during the enrollment process. For more information, see Troubleshooting co-management: Auto-enroll existing Configuration Manager-managed devices into Intune.