I find it funny when people say that if they opened the bottle a day later that it would fall apart. The range of ‘almost at it’s peak’ to ‘at it’s peak’ to ‘starting to decline’ can be several years in many cases.
I’d say precise statements are impossible. It’s sort of an uncertainty principle thing. If you know position absolutely, you have no knowledge of momentum. So if you know exactly how a bottle of wine is, you opened it (a measurement). And therefore you have zero knowledge where it’s going (wavefunction collapsed). Just like the cat in the box . . . .
You could comment on a wine being mature in a general sense, but saying it’s on a given point on the aging curve seems hard to project. Especially since each bottle is unique.
“fully mature” is a euphemism for “over the hill (but I own it).”
Akin to George Carlin’s bit on the difference between “stuff” and “sh!t.” If it’s your buddy’s wine, it’s over the hill. If it’s your’s, it’s fully mature.