The way it was explained to me:
Day 0 = Purchase Day
Day 1 = Tomorrow
Day 2 = Day After
Day 3 = Day After that
Day 4 = Day After that
In your case:
Day 0 = Today
Day 1 = Friday
Day 2 = Saturday
Day 3 = Sunday
Day 4 = Monday
So Sunday would be in the window and photos taken then would NOT included in the package.
Whether this is true or not, I never confirmed.
Our "Day 3" was our arrival day and we only got into the park just before it closed (back during EPCOT After Hours), so we didn't bother taking any pictures.
Now I wish I would have because it would have confirmed the timing.