T and I have an agreement that if something comes up and I can't make an appointment to just email her it doesn't need to be an emergency it could be something came up at school or whatever. She knows I never miss appointments and definitely wouldn't be a "no call no show". So if I am late she will check her email it'd it were an emergency I would call and leave a message. If I didn't contact her she would call me. This has happened a couple of times where I had written site a later time.