@Eakkawee *********
, That is incorrect information. The last day would never be postponed and it is as on stamp regardless of what day of the week. So if you go on Monday, it's the next day of your last day, You will get an overstay stamp. Just an overstay fine would be waived because the office is closed during holiday/weekend.
And agree, It'd definitely look better to go before the weekend than getting an overstay stamp.