You should cut as low as you possibly can, down to 1" or so if possible.
You should continue to mow as you normally would and do your best to stay off the lawn anymore than necessary. You can mow a few weeks after seeding. An important key is to
make sure you do not mow wet grass or over wet soil, then you can tear and pull up the new seedlings. Since you have to water a lot to keep the new seedlings moist, the key is to not water one time so that it dries just a bit, mow, then water immediately afterwards to keep the water on the seedlings.
Not sure I fully understand. You're saying it's safe
to cut as low as 1" before aerating/seeding? Wouldn't that kind of scalping hurt it big-time? Even if only once?
You then say mow "normally" a few weeks after seeding. I take that to mean the process should be:
Cut to 1" (not all in one pass, I take it--over a couple of days?)
Water briefly 2x day (and at least a 1" drenching once a week)
Do not mow until all the seedlings are up.
Since KBG won't even germinate for three weeks, then another month to be robust enough to take the blade, won't I have an overgrown mess of a lawn by then? I normally cut to 3" (3.5 in high summer).