A visible class timetable is important for all students. For younger students this should be visual with words, for older students this can just be words. When a change is going to occur make the change on the timetable with the student. Explain what the change is and why the change is happening. Do this as much in advance of the change as possible.
You can find many timetable options through Twinkl. You can also create your own through Twinkl Create.