A guide on this would be pretty helpful wouldn't it? :)
When the old man first has the egg, the second half of the PID is set. To answer your question about whether or not the old man will have the egg, read
this post. With this half set, the baby's gender and ability will always be the same, so you can have an idea of what frame you hit by eliminating the the frames that you couldn't have hit.
The first half of the PID and the IVs are set once you pick up the egg.
When you find the IV frame you hit, look at the PID of that frame. The second half of the PID will be the first half of the baby's PID. Use this half to test the PID halves you may have hit when the old man first held the egg (combine the halves and see if the nature it yields matches that of the baby's).
It's not perfect, I know, but if you calibrated with Spinda properly, it should be doable.
Edit: I'm writing this based on my experience from breeding with the older version of RNG reporter. I haven't looked at the new one's R/S breeding tools.