If my kids' school dismisses at 3pm & the bus ride home is 5 minutes at

[SuperKelly]

most, what time should I expect them? They are 12 and 14. I know they have to do kid stuff and say goodbye and all that, but and I crazy to want them walking in the door no later than 3:20? Should I cut them some slack? I do consider them trustworthy, have never had any problems with them. They both have cell phones also.
They go to school on my university campus so it's a university bus...I take the same one to class every day. I takes like no more than 5 minutes to walk to the bustop and get off on campus because the buses run continually.