I understand the workflow; I used to do that myself. What I'm suggesting is that there's an improvement :-)
When your delegate hands you the completed report, you go look in the relevant context and mark off the task as complete, whether the start date has arrived or not. You have to do that in your workflow as well, so there really is no drawback. You don't want to be delegating actions without some sort of accountability, so putting a start date for when you expect to have gotten a response is a good thing, not something to be avoided.
On the Mac, you could use the "
Where in OF" script to do a search for tasks in your on-hold context that had passed their start date. You can't make a perspective, though, and it doesn't help you in the slightest on the iPad.