  Neutrinos from a Galactic core-collapse supernova will be measured by
neutrino detectors minutes to days before an optical signal reaches Earth. We
present a novel calculation showing the ability of current and near-future
neutrino detectors to make fast predictions of the progenitor distance and
place constraints on the zero-age main sequence mass in order to inform the
observing strategy for electromagnetic follow-up. We show that for typical
Galactic supernovae, the distance can be constrained with an uncertainty of
$\sim$5\% using IceCube or Hyper-K and, furthermore, the zero-age main sequence
mass can be constrained for extremal values of compactness.
