Adding appointments to your system calendar is good, providing that you access it each day to check on where you need to be and what you have to do. However, there is one simple thing that you can do which allows you to be alerted to remember your appointment
When setting up a new appointment within the calendar, you have the option to show a more fuller form by clicking on the "I want more options" button. If you've already setup your appointment, then you can simply click on the appointment within the calendar section and the same editor will appear so you can amend it to add in the reminder.
You should see this form:
Circled, is where you set the reminder.
By clicking in the first box on the left hand side (closest to "Remind on:") you will be greeted with various dates that you can select one from in order to set the date of the reminder. This is up to you, it could be the day before or even on the day of the actual appointment.
Once you've selected the day, now you can edit the time of the appointment by clicking in the box to the right of the date box. Here, you will be met with the option to select the actual time that the system will email you a reminder.
With these options completed, you can click on the green "Save This Event" button and you will now be reminded via email about your upcoming appointment.
Below is an example of the email that will be popping into your inbox to nudge you about that all important appointment!