When you register an account on Appointment Reminder all reminders will be sent 24 hours before the time of the Appointment.
If you wish to change this, follow these instructions.
Note: You can also change the default send time for each specific calendar. To do this
If you want your reminders to go at a specific time for example 1pm the day before the appointment then choose the “Custom” option. In the days before enter 1. If you wanted the reminder to go 7 days before you would enter 7.
Note you can also change each individual appointment when creating them in the Appointment Reminder calendar or in Outlook Calendar. Setting the default send time is a great way to speed up the process of entering appointments.
If you want to send multiple reminders at different times then please check out how to setup sequences.