Can I report my education visa on Monday if the deadline falls on Sunday without facing an overstay?

The 90days report can be done 15 days before to 7 days after the date. But it has NOTHING to do with overstay.

If you're talking about extending, not reporting, then you can do it up to 30 days in advance - even 45 in some provinces, I think. So not needed to wait until last day. If the limit date is on Sunday or official holiday you can do it the very next day without any overstay but if anything goes wrong you'll get an overstay so no point in not do it in advance. Just do it tomorrow.

If you Admitted to stay period ends on 27th, you can go 30 days before this day to apply for an Extension of Stay. No need to wait till the last day and the Extension will be added on your current stay.

What kind of report do you need to do?