Odd, I was watching a recent ludicrous feed and someone tested the chrome extension on there and it seemed to work.. different link perhaps? Veda was on the stream too.
The way I found mine was on the manage vehicle page or the dashboard.
After authenticating,
this link should give you some text with "vin" in it.
Otherwise searching on the actual page that shows your purchase order in the source code for LRW.. if it isn't there, it isn't there
I guess another thing to point out here is that you most likely won't see anything until 1 1/2 months out from your expected delivery date.
Oh and one other thing; the Tesla website is all sorts of broken.
So expect things to disappear and reappear every so often.