I was just practicing the strat I came up with, and it turns out if you go to the generator, you can interrupt the line sooner. We can either save it for another dialogue skip, or use it here.

Ok so when D call the Service Forest, if you launch the "Generator" question, D skip the waiting time ?

It doesn't appear to be any faster, going to the generator. I went to the generator, the outhouse, and used the Forest Byrnes sign and they all appeared to be the exact same time. Unless I am simply missing something, it appears that any dialogue skip triggers the line at the same time.