I think, like being queer, there is no clear answer, and looking for one is kind of missing the point?
Like, does it matter whether someone is queer or gender non conforming from birth or from last Tuesday, to anyone who's not a massive piece of shit?
And trying to answer that definitively kills a bunch of nuance and creates lots of biphobia and is just generally awful.
Furs are pretty similar there. Are you this thing? Do you like to do this thing? Have you always wanted to try this thing? These can all have different answers, or the same, and it's fine.