By setting up timezones for your appointments, you can easily operate within multiple timezones/regions and send off reminders at appropriate local times.
Check your company timezone
Settings > Company Details
Start by ensuring you have selected the correct timezone that your company primarily operates in.
Check your System Defaults
Settings > System Defaults > Calendar
If you do operate within multiple regions, make sure the first timezone option is unchecked (Hide option of selecting a timezone when creating/editing appointments). This will allow you to change the timezone for each appointment that you create.
The second option (always show timezone details regardless of appointment location) allows you to display a timezone indicator even for appointments located within the same region that you primarily operate in.
Appointments outside of your company timezone will always have an indicator of its timezone.
Now that you've set up the basics, you can create new appointments with different timezones.
The timezone selector will automatically use the company timezone, but you can change this to the correct timezone.
Selecting the correct timezone is important to ensure that reminders for staff and clients are sent off at the correct local time.
Check Staff Availability
In the create/edit dialog, clicking Staff > Check Staff Availability will check and make sure that each staff member is free for this timeslot. It will account for timezone overlaps/differences.
It will also suggest other staff members who are also available in a timeslot.
On your calendar, appointments will be marked with a timezone indicator before the appointment title.
Clicking on an appointment will display full timezone details