org-icalendar-use-scheduled

org-icalendar-use-scheduled is a variable defined in `ox-icalendar.el'.
Its value is

(todo-start)

Documentation:
Contexts where iCalendar export should use a scheduling time stamp.

This is a list with several symbols in it. Valid symbol are:
`event-if-todo' Scheduling time stamps in TODO entries become an event.
`event-if-not-todo' Scheduling time stamps in non-TODO entries become an event.
`todo-start' Scheduling time stamps in TODO entries become start date.
Some calendar applications show TODO entries only after
that date.

You can customize this variable.