This feature is available in Ultimate edition only.
If you have a long-running project without an end date and do not use releases in your project tree, use the planned start and planned end dates on projects to drive the timeline display.
From the main menu, select Product Planning, and then click Project Timeline.
Select a project from the Project Navigator.
Click on the ID of a project for which you want to set start/end dates. The Details page opens for the selected project.
Click Edit, then click on the Begin Date field. A pop-up calendar opens for you to select a start date for the project. Do the same for the End Date field.
Click Save. The dates you have entered override any dates inherited from the master project.