Microsoft Visio - Adding Milestones
Milestones represent specific times when an important event has occurred or is due to occur. To add a milestone, click and drag the Milestone Line shape to a chosen interval on the timeline. It is not necessary to delete it exactly at a specific interval, as you can manually configure the exact date and time of the event.
When you drag the milestone onto the timeline, the Configure Milestone dialog box appears, where you can specify the exact date and the milestone time with a deion of the event. You can also choose from standard date formats to better represent the time and date. Click OK to create the milestone on the timeline. The milestone can be moved along the timeline, and the milestone date and time will be updated accordingly.