Baby, You Can Drive My Start

Have you ever had to manage a project where the start date for the project was driven by a task other than the first task in the schedule?

In most cases, you set the start date for your project by entering the desired date in the Project Information dialog box. The first task in your plan would begin on the Project Start date specified, and all other tasks would be scheduled based upon their dependencies and constraints.

However, many times a task other than the first task in the plan is the real driver for when a project should begin. Let's consider the following scenario: Suppose you had to deliver a software prototype to your client on a specific date, and you wanted Microsoft Project to calculate when the project needed to start in order to meet this date. Note that the delivery of the prototype is not the last task in the plan, so it is not simply a matter of telling Microsoft Project to schedule the project from the specified "Project Finish Date".

In the example shown below, I have created a simple schedule where the project start date defaults to the current date of 7/18/2006, and the task "Present prototype to client" is calculated to begin on 8/7/2006.



I would like the "Present prototype to client" task to begin on 8/23/2006, and to accomplish this, I enter this date in the Start field for the task. Using this task as the driver, I would like Microsoft Project to figure out when my project needs to start in order to be able to meet the date specified for the "Present prototype to client" task.

After entering the date for the "Present prototype to client" task, notice that the dates of its two predecessor tasks have not changed (see below). This is because their constraint type is set to "As Soon As Possible".



To achieve the desired behavior, I will insert the column "Constraint Type" in my table and set the constraint type for the two predecessor tasks to be "As Late As Possible" (see below). Notice how the two predecessor tasks are now rescheduled to begin as late as they possibly can in order to allow the date for the "Present prototype to client" task to begin on 8/23/2006. Mission accomplished.



Another technique for accomplishing this same behavior is by changing the task dependencies for the first three tasks in the project. Here's how it works:

• First, highlight the first three tasks in the project, and click the "Unlink Tasks" button (see below).

  

• Next, insert the Successors column, and make Task 2 a successor of Task 3 with a Start to Finish relationship. To accomplish this, enter "2SF" in the Successors column for Task 3 (I bet this is the first time you have actually used a Start to Finish relationship!)

  Note: Since Task 3 already has a successor, we will separate each successor with a comma.

• Finally, in the Successors column for Task 2, make Task 1 a successor of Task 2 with a Start to Finish relationship (enter "1SF" in the Successors column for Task 2).
  
  
  
  Notice that the start of the "Present prototype to client" milestone is driving the finish of Task 2, and the start of Task 2 is driving the finish of Task 1. If you were to reschedule the "Present prototype to client" milestone, all of the other tasks in the project will be rescheduled appropriately. Very cool!