Yes, I thought it was based on time of having baby too, based on what they told me when I had DS, who was born mid morning. I remember them saying to me the next day that he was 2 days old and I said, "no, he was only born yesterday", and they explained something about when they take it from, but maybe thats a different 'day' than the way they work out the duration of your stay.

Best to check with the Dr and then probably recheck with the hospital!
I would guess you`d go home on the Saturday...?