There isn't really a normal age to awaken Skeeve.
Some people don't awaken at all while some are, although very rare, already awake when they are born.
There are some that are quite literally in the process of dying when they finally tap into their memories so the life flashing before them is not the one just lived but another much longer and older one.
Quite often awakening takes many years so that the person is steadily made ready to accept the changes it involves, while the very rarest cases go with a bump almost over night.
Sometimes like John Smith in Deadzone a traumatic incident powers the awakening process.
And sometimes, for the lucky ones, parents are Kin and can help things along.
I know it didn't specifically answer your question but I think I covered all the possibilities.
Incidentally
I have spent some physical times as a Wolf but just as now I am in a human skin, I was then a phoenix in a wolfs body.
Oddly enough from what I remember I actually fit better in a canine skin than I do in a human shaped one.
Wierd huh
Zygo