Automatic updates of timeline activity dates
The default timeline that is specified in the Case Types configuration allows you to specify the reference activity (i.e. which activity should provide the reference point for any time offset) and the amount of the offset (i.e. how many days before/after) for any given activity that is going to be in the default timeline. So, in your example, you want 'Course Start Date' to be the reference for all subsequent activities.

Having said that, when you create the case, I think that all the offset calculations are done at that point in time, so even if you then subsequently set a date for the 'Course Start Date' activity, I don't think subsequent activity dates will automagically adjust as we might like them to.