Don't do it yet.
I have a 2018 Model X that got 2014.20.1 ("v12") last week, and I would not recommend it. Several of my touchscreen buttons now don't work (Close All, Front Trunk, and Trunk). The trunks work from the key fob, so I know it's not a mechanical issue. Also, driver profiles no longer adjust the seat and mirrors, a luxury I had become surprisingly reliant on. I have logged bug reports through the voice control system.
When I scheduled a service request with those issues listed, the first available appointment was August 2(!) and the estimate was $153 for diagnostics. No thanks. I'm trying to find any other references to this update to see if these issues are pervasive. Hoping they are fixed in the next update.
YMMV.
-DDR