I've posted about this before, but let me try again. I cannot figure out the proper use-case for appointmentsa in Toodledo. Basically, as I understand it, an appointment is an event with a start and end time (and, by implication, a length). The question is how to represent it in Toodledo.
1. If you represent it with a due date and length (to me, the natural way), the appt will show up on your iCal calendar as starting at due-length. If this acceptable, then, if the length is strange, Toodledo does not give you a natural alarm for the appt (you have to add length to the alarm time you want). If this is not acceptable (you assume the meeting runs from due to due+length), then you iCal calendar has the wrong time for the start of the appt.
2. If you represent it with a start and due, the iCal calendar will look correct, but again there will be no natural alarm for the appt.
3. If you represent it with start, due, and length, then what does it mean if your length is not equal to due-start?
4. If you represent it as start=due, then your alarm will be natural and the iCAL calendar will look right for start times, but not end times. Also, the length will not make sense.
Toodledo was designed to be a task manager, so it is a bit of a stretch for it to also manage calendar appointments which is why you are having difficulty. What we should do is make a way for alarms to be relative to the start-time. Since we don't have this yet, you will need to decide if it is more important to:
1) Have the event look correct on iCal (proper start/due times), but have an alarm relative to the due-date.
2) Have a proper alarm, but have it look wrong on iCal (start/due time the same).