I see Robin and I posted pretty much simultaneously.
The neutrinos from SN1987a came in a clump a few seconds long. The telescope wasn’t very sensitive and the SN was at quite a distance so it’s likely that it saw only the very peak of the neutrino curve.
However, core collapse is a very rapid process, on the timescale of a minute or so (hence my prediction), and there is no obvious intense source of neutrino emission afterwards. Once the neutrinos get outside the core everything else lying in our direction is essentially transparent so they will not be scattered as is the initial burst of photons.