Change an activity's start and finish dates in the Gantt Chart

Move the mouse pointer over the activity’s Gantt Chart bar end until it displays a hand pointer.
Click and hold the mouse button.

To move the activity’s start date and finish date back in time, drag the bar to the left.

To move the activity’s start date and finish date forward in time, drag the bar to the right.

Notes

You cannot move the activity if the activity has already started.
Changing a bar’s position in the Gantt Chart does not affect activity duration.
When you change a start or finish date, depending on your application settings, a dialog box may display to prompt you to enter a constraint. To accept the constraint, click Yes in the Confirmation dialog box. If you specify start and/or finish dates without applying Must Start On or Must Finish On constraints, the dates you enter may be changed when the project is scheduled.
If resources are assigned to the activity, and the resource assignment has manual future period values, the values may be affected when you change the activity start or finish dates.