A good routine is not a rigid schedule timed to the minute. It is a predictable rhythm, a familiar order to the day that both of you can rely on.
Start by finding your person's best window. Most people have better hours (often the morning) and harder ones (often late afternoon and evening, sometimes called sundowning). Put the demanding things, bathing, appointments, outings, in the good window, when their brain has the most to give. Keep the hard hours calm, quiet, and low demand.
Anchor the day with familiar, repeated touchpoints: waking, meals, a daily walk, an afternoon rest, a calming evening wind down. These anchors do not have to happen at exact times, but they should happen in a consistent order. The order is what the brain holds onto.
Build in gentle transitions. Abrupt shifts are hard, so give a warm heads up and move slowly from one activity to the next.
And design it for both of you. A routine that runs you into the ground is not sustainable, and your wellbeing is part of the care. Build in moments that give you a breath: a quiet coffee, a task your person can do alongside you, a predictable rest period you can both count on.
A rhythm that fits your real life, and that you can keep, beats a perfect schedule you cannot.