Project sets the plan’s start date to current date, a thin green vertical line in the chart portion of the Gantt Chart View indicates this current date. Exceptions are used to modify a Project calendar to have a non-standard workday or a non-working day.
Let us change the project start date and add some more information. Select a Standard Calendar as your project Calendar. You can also allot unique working hours for a particular resource as well.
You can modify the resource calendar to accommodate flex-time, vacation time, training time, etc.
Also remember, Resource Calendar can only be applied to work resources and not to material and cost resources.
Because once you enter one of the two, and other project tasks, constraints and dependencies, MS Project will calculate the other date.