We know that every single human being has a Guardian Angel
assigned to them the instant they are conceived. We know the names
of two Guardian Angels, Raphael and Gabriel, because they are in
the Bible. And we know from private Revelation that God assigns
groups of people a special Guardian Angel, as at Fatima, the angel
revealed that he was the Guardian Angel of Portugal. Outside of
that, I don't know if God assigns angels for things like days of
the week.