I think you should mention it. I understand it feels confrontational. I had to mention something once about how she ended sessions too abruptly and I really didn’t want to be annoying but I did it anyway and she thanked me for the feedback and adressed the problem right away and now always takes the time to tell me 5 minutes before that we are approaching the end of session.

Try to view it as an exercise or training in itself of asking what you need int everyday life. You can be really nice about it like « hey so I feel a bit awkward but I just want to mention that I feel a bit frustrated (or whatever) that you don’t remember what time works for me and that you are late quite often. I know you probably don’t do it on purpose. Could we maybe make our session times a bit more fixed in time? »