Lateness is surprisingly common and is usually the result of absent-mindedness rather than blatant rudeness. However it is not a good start to a session with a Mistress if your first act is to treat her time with such disrespect as to be late for your session.
It is almost as rude to be early and of course there is no excuse for it because if you are there early, waiting a few minutes is always an option.
My suggestion is that you make your determination to be punctual your first act of the session - your first act of submission to me. Think of me, your Mistress, in my apartment, knowing that you are due to arrive at the prescribed time. Give yourself plenty of time and plan to arrive in the area early so that if any delays should occur they won't make you late. Go for a coffee or sit in your car waiting for the time of your appointment to arrive. Enjoy this time as you prepare yourself for what is to come. Enjoy the increasing nervousness and anxiety as the moment when you stand before my door waiting for me to open it approaches.
If you are late it is very unlikely I will go ahead with the session and if I do it is very unlikely that i will move the finish time do accomodate your rudeness.
If you do all this and something unforeseeable (not traffic - traffic is foreseeable!) happens that will cause you to be late - then let me know immediately by phone. I will listen to your excuse and decide whether your rudeness has made me too angry to proceed.
If you are not prepared to abide by the above rules then please do not contact me for an appointment.