When a job is opened from an estimate, milestone hours are automatically set for each form based on the estimated hours.  The hours are assigned by form using each operation's assigned milestone.  Once a milestone is defined you can associate operations with that milestone from Operations Setup.

It is common to link several operations to a single milestone.  For example, Press Makeready, Run and Wash operations will link combine the hours into a single Milestone for scheduling purposes.  Prepress functions also commonly route to a single Prepress milestone.