There are people in this group who are very opposed to Schedule by Completion Date. Therefore, I have tried it both ways – by Start Date (and make a Must Finish By the last task in the project) or by Completion Date and allow the project to tell you when it should have started (pretty much always in the past, we are late launching almost everything). We too have very hard date completion dates, so I am most comfortable with the Completion Date method because it tells you right away how many days off your plan is. So if today, I launch a project that has a template that takes 40 days, and the deadline 20 days away, the first task calculates a due date 20 days in the past, and I can keep adjusting the durations until the first task is set for today, so I can easily launch a project without it already being late. I find it very hard to do this with the Schedule by Start Date because I find it hard to see where the plan gets bunched up and by how many days it's bunched up, and whether I have fixed it when I change the durations. The main downside (for me) is after the project has started and several tasks on the critical path are at 100%, and when I recalibrate the remaining schedule, the project doesn't recalculate properly to the completion date. The only way to fix that to get a new plan that properly counts the days, is to find the first task in the critical path and set a Must Start By date on that task. I still have trouble telling if my new plan is working, but then I look at a couple key dates (i.e. release to printer) in the middle of the project to see if they are correct (which means getting out the actual physical calendar and making sure I am counting the days correctly) and I also use the status icons on each task to see if any turn red. When I use Schedule by Start Date, and the last task is Must Finish By, I have a lot of trouble getting it all to work and to figure out how many days my plan is wrong. Finding the red icons, and trying to mash 40 days into 20 is much harder for me this way. I would love to hear how other people manage it, it's a big question I have too.