Odd and irrelevant.I don't take it as being ambiguous at all. If they say the mom took the kid out of school "early," then you can't tell me that it means anything other than, prior to when the kid is normally supposed to leave school.
And I agree that it is the mother's prerogative to take her son out of school. However, it is odd that she would take him out of school, on Tuesday, just so he could shooting.