People say write appointments etc in a large calendar, that is fine it the person remembers to check the calendar!
I've hung my Dad's calendar on the wall next to where he sits at the table to eat his breakfast.
I wouldn't necessarily expect to rely on him reading it for himself, though if he's forgotten something I'll remind him it's on his calendar.
He goes to a day centre four days a week so I write that on, plus what time he's being picked up in the morning and what time he'll be home by.
He calls this "going to work."
Anything out of that routine I write on and highlight eg dentist appointment, hospital appointment, where, what time and who's taking him.
Similarly if we're taking him out for the day or away for the weekend I write all the arrangements on so the carers know that he will be out of the apartment, what times, where he's going, who with and that he won't need any meals.
They manage his medication so I need to collect that if we take him away overnight.
I also write on when my husband and I are away so they know to contact my brother or sister if there's an emergency.
Obviously I tell them any news in person as well, but Dad has a team of carers and I don't see all of them every week.
They've all said they find the calendar extremely helpful to be able to refer to 🙂