There should be away that we can flag an appointment on the book (make it red) for important notes, reminders or if they have a habit of being late or not showing up to their appointments. This can also be combined for Birthday reminders.
What I do now is before their appointment time I make a break time before and write my notes there.
I was thinking maybe having an option to flag the appointment and make it Red so on the appointment book it stands out when looking at it