The InstanceDate property returns the date on which an instance of a recurring item is an exception.
Exception object
Date
Read/write
The date specified in the InstanceDate property is the date on which the recurring item would have occurred if it were not an exception.
For example, suppose that an instance of a recurring appointment is scheduled to occur on 10/14/95, but the user moves that instance of the appointment to 10/21/95. When the appointment is moved to the new date, Schedule+ creates a new entry in the Exceptions table with its InstanceDate property set to 10/14/95 and its Start property set to 10/21/95.