So, on twitter, they confirm all this does is check for the update. If your car is set to get it, then you get it. The original post looks like it's some magic to get you the update when you weren't already slated to get it.
The automatic process your car has to check when you are ready to get (showing you the download arrow if not on wifi) or download it if on wifi is probably every couple of hours. This probably bypasses that. Cool, but not exactly groundbreaking. It's like the triple tap to bypass the 2:00 minute timer to start an update in the car immediately.
Sorry for the confusion, but the OP sounded like you get it now now now no matter what.
Both my cars got it in the last three days, with the 3 getting it last night, when most of them did.