That's a great question, but I think that there's more to determining when an organism is ready to reproduce than cellular age.
If you air-layer, the resultant rooted cutting will be the same cellular age as the donor branch, which may be a different cellular age than the
root stock that it was grafted to,
should it be grafted stock.
I think that if a tiny little cutting too small to support a flower, let alone an
apple, decided it wanted to expend all that
energy to fruit, it wouldn't be good for the rooted cutting, which should be working on its root zone and aboveground vegetative growth. So I would think about pinching off that bud, to that end.
But to
answer your question, an air-layered rooted cutting, like any grafting, is a clone of that part of the organism from which that cutting was taken.
If the tree is the infrastructure that the fruit need to develop, what kind of result would you expect from seedlings a year after being cut? Fruit
trees usually take at least three years before they begin growing in earnest after replanting. Where are the resources, the nutrients and
water, and the food energy from the sun and its interaction with chlorophyll, that the plant will need to fruit, if there's no root zone or leaves to collect them?
So even if they did fruit on you within a year, it would probably kill them.
-CK
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
-Robert A. Heinlein