KENNEDY
Doesn't work that way. In fact, the younger, the better. In fact, I'm starting to think it might be too late for me.
EVE
Never too late. It could be anyone. Especially since there's so few of us left. They'll just run through each one of us, one after the other. Kinda creepy, huh? All we do is wait around for each other to die.
Showtime
Eve/The first said it is never to late, I think that is true.Ok we know the power is not predetermined, u never know who will be the next slayer, it cant be predetermined because u never know how long a slayer will live, but we have seen through the series that it usually goes to a slayer of about 16/17. exceptions being nikki woods, Xin Rong(Boxer rebellion Slayer, is that right) and the first slayer they were not around 16/17 when activated, I'm guessing because they are older and the whole not live very long thing.
Ok now the speculation I think that when a slayer dies the power will choose a random girl, it will aim for a someone between 16-20, but if there is none between these ages it will go 2 another, because u are born with the potential and u never loose it. The first says "Especially since there's so few of us left. They'll just run through each one of us" that's is what leads me to think this true.
Another theory is maybe u can get too old to be a slayer, when we see the slayers being activated we saw a 8/9yr old girl being activated and the rest were about 16-20 we do not see anyone 30 or over, so maybe u can loose ur potentialness.