well, for one thing, Males, IME, tend to have more wrinkles than Females. so the fact that Lulu is female could have something to do with it.
as far as when wrinkles show up, i've noticed with my dog, it depends what he's doing. if he's walking down stairs, you can't even see his eyes because the skin falls over his eyes!
however, if he's looking up at me, the skin is pulling down on his face, and he doesn't look too wrinkly at all.
but by the time he was 1 years old, he definitely had extra skin.
but i don't think wrinkles in general are necessarily a characteristic of a pure-bred basset - the fact that Lulu is without too many doesn't mean she's not a great Basset!