How to add time-dependent actions in Lightning Process Builder?
Scheduled actions are only available in two cases.
On the object node, the process is set to "Start the process only when a record is created." All criteria will then have the Scheduled Actions option available.
On the object node, the process is set to "Start the process when a record is created or edited", AND on the criteria node, the checkbox "Do you want to execute the actions only when specified changes are made to the record?" is checked. Only criteria on which this is checked will have the Scheduled Actions option available.
So, that means you can't do time-dependant actions if your criteria includes IsChanged. Because when you set the checkbox on the criteria node, it shows an error.
I had the top node created, but not set with the checkbox. But the Scheduled Actions box did not show. I moved the node to the bottom and it did show. Then I moved the same node to the top and it sill showed. Weird. And yes I did exit process builder a few times to check.
But I don't trust Time Based Actions in Process Builder that much, that I just created a new Checkbox field and set that via a Workflow, and then made my Chatter Post go when that checkbox is set.