Plan Your Timetable is a planning tool that allows you to experiment with different combinations of classes (e.g. lectures/tutorials) prior to formally registering into your classes via eStudent. You cannot formally register into your classes via Plan Your Timetable.
A benefit of Plan Your Timetable is that it allows you to “test out” different combinations of units prior to enrolment (this is useful if you are choosing between options or electives). You cannot do this in eStudent, as it only allows you to see the units that you are already enrolled into. Additionally, registering and unregistering into classes for the purposes of planning adds to the processing load of eStudent and it can be quite slow.
Please note that Plan Your Timetable does not contain live data on full classes or units. You may find that you when you go to formally register your timetable based on your plan you are unable to do so due to full units or classes. You have until the end of the second week of semester to change your timetable around so if you cannot get into your first preference of class, it is advisable to keep trying.