Currently there is no way to add the full date property to a calculated string property.
Best current option is to write a workflow to update a text field every time the date is created or updated or live with MM/YYYY using the following formula = number_to_string(month([DATE PROPERTY])), “/”, number_to_string(year([DATE PROPERTY]))
Seems like an easy fix to add a date to string (or DateFormat) or add a day of month function.