Start with the fixed appointment
Put the tour, performance or reservation that cannot move into the plan first. Add the time you need to arrive before it begins. A ticket start time isn't the moment to reach the car park.
If nothing is fixed, choose the activity that matters most and give it the best part of the day.
Map the route from door to door
Use exact locations for the start, each stop and the finish. Look for backtracking. Two appealing places can make a poor pair if moving between them consumes the time you wanted to spend there.
Include meals and the return journey as real parts of the schedule.
Mark the first thing to drop
Choose one optional stop that can disappear without spoiling the day. Tell the group which one it is. If you start late, remove it rather than shortening every visit.
Build the sequence in your Outxie plan, then check the actual bookings separately. A good itinerary explains what matters and what can change; it doesn't need an activity in every empty space.
Rules, fees and opening hours change. Confirm anything that matters before you rely on it.