You can add these dates from the project tracker in the project, per item. To do so you would click the magnifying glass to the left of the item you want to add the date for in the project tracker. This will open a pop-up window with all of the details for that item. Then you would click the "Schedule" tab within that pop-up window and there you can add all of the tracking dates.

You can also edit more than one project tracker items/shipping dates at the same time by  clicking on the items check boxes and pressing the blue "Edit All Checked" button on the top right.