If you take over a low rated "D" school and recruit with that prestige during the first recruiting period, then make the NT after a good turnaround year and improve your prestige to "C"....do you get credit at the "C" level for the effort you put forth on a recruit during the first recruiting period when you were recruiting at a "D" (assuming they haven't signed, of course)?

It is definitely not retroactive. Attention points and visits made in the first session retain first session credit.

I *think* the system was supposed to value the second session effort with the new prestige modifier in effect, at least that was how it was discussed during beta, if I recall correctly. However, I’m not sure it actually does that. I’ve seen folks claim both, and I don’t recall if anyone has asked CS specifically.