Private footprints
If you do want to create a footprint with the private switch turned on, for example, to edit it on multiple devices, please do so; it is a good practice.
When turning off the private switch for the first time, notifications of the new post will be sent to your followers.
Planned footprints
Planned footprints are private. When you turn off the planned switch for a footprint, it is not private anymore and will be visible to your followers. Your followers will then be notified of the new post.