Here is a quick video that will show you how you can set up a reminder for your customer either the night before or day of the appointment (SMS/text message only)
To enable this, go into the Settings (cog top right of the home page) and then into Communication & Reminders
Then in there under the Customer Appointment Notifications tab will be a section for Appointment Reminders
Here you can set up the reminder for your customer to either go out the day of or day before the appointment. There is a third option where you can set it so any appointments in the morning will have a reminder sent out the day before, however any appointments for the afternoon will get reminded the day of the appointment. Once you have chosen which day the appointment goes out, you can decide what time of day the appointment goes out.