If you're making changes to your fixed date or property-based workflow, you may notice that you are unable to change the timing of one of your delays. This happens if the attempted change will cause the delay to be out of order in the workflow.
For example, you have a workflow with three delays as follows:
Delay 1 is set for 7 days before 9/1 at 12:00pm
Delay 2 is set for 2 days before 9/1 at 12:00pm
Delay 3 is set for 9/1 at 12:00pm
If you attempt to edit Delay 2, you will be unable to change the time of the delay to anything prior to 7 days before 9/1 at 12:00pm, as this would put these delays out of order.
The same is true if you're trying to edit a delay to make it occur later. If the attempted edit would set the delay for a later time than another action further along in the workflow, you will not be able to make the change.