Have you ever had to coordinate several family or business activities without having full knowledge of everyone’s schedule? It is kind of like playing the video game Tetris with time instead of with funky looking blocks. If you have not played Tetris, the goal is to get uniquely shaped objects to fit together before they crash into the already placed blocks. As you advance through the game, the blocks move faster, making it more difficult to place them.
Forget about accelerating the pace for the moment…devising a project schedule can often feel like playing Tetris. Instead of fighting faster moving objects, you are likely trying to deliver the schedule on deadline. You have the effort estimates for your project, now you can begin the exciting task of determining how all the activities fit together.
Disclaimer: this topic – defining a project schedule – could take several blog posts if I were to cover all the various components of scheduling. In an attempt to keep things simple, I will cover the basics then link to other sites that cover some of the details.
Tetris Blocks
How do you start putting together your project schedule? The best place to start is with your Effort estimates. Remember, these tell you how many hours it should take to complete a task. Next, you should work with the managers of each person on your project team and confirm your team’s availability.
Say your Business Analyst is available four hours per day for an 80-hour task. That means they will require twenty days to complete it (80 hours / 4 hours per day = 20 days). However, your Solution Architect is available six hours per day for their 90-hour task. They should complete that task in fifteen days (90 hours / 6 hours per day = 15 days).
Doing this math with all of your tasks confirms your estimated durations. Congratulations, you have just built your Tetris blocks. How do you make them fit together?
Sequencing Tasks = Fitting Blocks In Place
Looking at your WBS, consider the order in which all the tasks need to occur:
- Which need to occur before others can begin? These are prerequisite tasks.
- Which have no prerequisites, but should not occur until a certain stage of the project?
- Which activities can be run at the same time (i.e. in parallel)?
Most likely, your WBS is structured in a way that is already somewhat sequence-based. For example, in the Demand Management project, you cannot evaluate software products until you have identified which products are available. Also, you cannot test the system until it has been set up.
Conversely, for the Basement portion of the home building project, maybe the Water Heater and Gas Furnace work can occur at the same time, because it involves different people at a different place in the basement. And maybe the recreation room can be constructed while the water heater and furnace work is being done.
Software Makes Playing Tetris Easier
Playing Tetris with time becomes easier if you use scheduling software. Linking activities (i.e. assigning prerequisites) and assigning start dates to activities that have no prerequisites should enable the software to calculate your start and end dates for each task.
At this point, your schedule should have a start and end date, and all tasks should be sequenced in a way that looks operationally feasible. You may have to consider company holidays and teammates’ vacation times when evaluating whether your schedule needs to be tweaked. You may also need to look at your vendors’ holiday schedules if they are based in a different country.
By using scheduling software, you not only compute your project start and end dates, but you get start and end dates for each phase of the project, too. This is handy for showing your costs and estimates by phase, so your accounting team knows when to make funds available.
Winning at Tetris (Takeaways)
There you have it! Here is “Playing Tetris with Time”, the way-too-oversimplified version of building a project schedule. Once you have your team availability and effort estimates, you can validate the duration of each task in your WBS. Once durations are confirmed, you can use scheduling software to link tasks together or set hard start dates for those that do not have prerequisites. The software tool will then define your start and end dates for each task, each phase, and the overall project.
For a deeper dive into project scheduling, I recommend studying the following topics:
What is a GANTT Chart? – a comprehensive explanation of what GANTT charts do and how to build them. Much of the information will look similar to what the Simple PM series has explained thus far.
Critical Path Method – what is a critical path and why is it important to your project schedule?
Note: I do not implicitly or formally endorse any software tools promoted at the articles to which I link.