Keeping a site production schedule can be a challenge. There are many factors that go into creating a production schedule and many are not unique to open source. When you add the unpredictability and lack of control often experienced with open source, your ability to predict a schedule and deliver a fixed set of features become a juggling act. Add to the mix potential learning curves and you can have a challenge on your hands if you assume anything is possible and promise it.
Below are some insights into scheduling a Drupal project.