Not sure how much help I can really be here as I don't personally have this issue but my 9 year old so and my 60 year old boss do. My boss's fix was easy, he hired me as his PA I organise his day completely including making sure I have his breakfast, lunch at work in the fridge, book in things like haircuts etc and make sure he attends all the things he should. I know this service is available through some online PA services. I wonder if something like this could work for you?
For my son I try to make his day extremely repetitve at the beginning and the end. Ie, wake up, breakfast, make lunch, pack bag, brush teeth. Then at night bath, teeth, read, uniform ready for tomorrow etc. My hope being that it will burn itself into his memory and he can make small adjustments as necessary through the years. Admittedly it's not working overly well at the moment and I am not the one with this issue so I don't know if what I am doing will be helpful or not. I just keep trying
Can I just quickly say though, and I am extremely sorry for going off topic. But you will never know how helpful you guys posting these topics is for us NT parents who are trying hard to understand our children who do have some challenges. It gives us information that our children may not yet be able to verbalise.It is absolutely invaluable. So .. yeah *hugs*