In the district I work in we can't mark a child absent until they've actually shown up for school. The first day we see them is considered the day they enroll, so any days they've missed before then don't count against them. For instance, if we started on a Mon, but Jr. doesn't make it in the door until Wed, then Mon. and Tues. don't count as absences because he didn't enroll until Wed. even though he's on my roster from day one. We always have parents who give their kids an extra couple days at home, it really doesn't bother me.