I think it would actually be more convenient for some parents for their children to start later rather than earlier because it would mean that the end time of school would be later.   I think for high school and maybe middle school students who could be more responsible for their getting to school independently or on the bus this could work.  Parents also would not have to leave home as early for work because they aren't dropping their kids off to school.  Middle school and highschool students who had later start times and perhaps more breaks during the day with spaced out instruction time and after school time would spend more time in school rather than having this large chunk of time after school unsupervised he while parents are working.  What if school was 9am-5pm and every student stayed till at least 5pm to do a sport, get tutoring if needed, have a place to study for homework, do arts, music or excurricilar activities.  This would benefit working parents and the students.