Vehicle software update necessary for this feature
While this feature is incredibly useful, it is important to note that you won't be able to use it unless you've updated your Tesla's software to version 2018.48.12. This paired with version 3.8.0 of the mobile will give you remote heating capabilities.
What else comes with this update?
Along with remote heating, this update also brings the capability to place a service request directly from within the app.
The appointment interface given by Tesla lets you pick the date, time, location of the service center of your choice as well as describe the problem you're facing.
But, as of now, most service centers appear pre-booked days in advance.