I've been lucky as blank slate T and new T, are NEVER late! They start right on time and end right on time. Well, one time my new T went over time but I don't think that anyone was waiting. I ended up emailing her asking if she was going to deduct from our next session and she said that it's her job to manage the time and of course she wasn't going to deduct from our next session.

I absolutely hate it when people are late and would not tolerate it with a T. Of course, once in a while is understandable but as a regular thing would bother me so much that I'd probably look for a new T. I would definitely talk about it first and if it didn't get better quickly, I'd move on.

Good luck with this!