Sorry to sound facetious but I found with mum routines were impractical. She would get up when she wanted, eat when she wanted. Shower on the days she decided.
All this despite gentle coaxing and sometimes even bribery in the form of her favourite biscuits ect.
Only advice I have is that it's pointless to argue with them, walk away and try again later. If your asked the same question 10 times never say I told you XYZ just repeat the answer.
May I suggest you join Talking Pount forum. Lots of helpful advice, and a place to rant if nesessary to people who understand including those who have been diagnosed.