How can you minimize or control changes to project schedules?

The first step in establishing a project is to estimate how long each activity will take, from the time it is started until the time it is finished. This duration estimate for each activity is the time for the work to be done plus associated waiting time. It's a good practice to have the person who will be responsible for performing a particular activity make the duration estimate for that activity. This generates a commitment from that person and avoids bias that may be introduced by having one person make the duration estimates for all the activity. An activity duration estimate must be based on the quantity of resources expected to be used on the activity. The estimate should be aggressive, yet realistic. Throughout the performance of the project some activities will take longer than their estimated duration, others will be done in less time than their estimated duration, and a few may conform to duration estimates exactly. Over the life of a project that involves many activities, such delays and accelerations will tend to cancel out one another. In order to establish a basis from which to calculate a schedule using the duration estimates for the activities, it's necessary to select the estimated start time and required completion time for overall project. These times define overall window or envelope, of time in which the project must be completed. The projects required completion time is normally part of the project objective and stated in the contract. Once the, estimated duration for each activity in the network and an overall window of time in which the project must be completed, you have to decide whether the activities can be done by the required completion time. An ever enjoyable aspect of managing a project is the control the project schedule. The managing and maintaining the schedule proactively is your best way to assure the project comes in on time. In order to be proactive about this process there are some inputs that one needs to understand. The inputs are: The Schedule Baseline - The schedule baseline is the current approved version of the project schedule which provides a basis for comparing and reporting on the project performance. The project schedule details the planned start and end dates for the activities. Performance Reports - Performance reports are first and foremost a communication mechanism to list what work has been performed by whom. A good performance report should show the planned and actual dates and duration of work activities Schedule Management Plan - The Schedule Management Plan details how changes to the schedule can be made and under which conditions such changes are allowed. Project Manager, Project Sponsors, and Functional Managers should adhere to the scheduling guidelines explained within the schedule management plan. Approved Change Requests - Approved schedule change requests are an input because the schedule needs to be revise to reflect the approved changes to the project schedule.