Ghavrel referred to some studies with numbers on that earlier. Obviously this 'rapid onset gender dysphoria', teenagers deciding seemingly out of nowhere (at least according to their parents) that they're trans, is highly controversial because anti-trans activists are using it, much like the women's sports issue, as a weapon against all transgender teenagers, while trans activists are denying that it's a thing at all, for the opposite reason.

And to be clear, the question of how easily/quickly puberty blockers should be available, particularly in such cases, is a very different one from whether they should be available to anyone at all. I can certainly empathize with parents who feel like this is all happening too fast (even if probably there are parents for whom it's only 'fast' because they'd been in denial about the signs earlier...), or with medical staff who are under heavy pressure from their patients to give their approval quickly even though they aren't convinced yet. Especially due to the long waiting lists for such medical staff - by the time trans teenagers get to actually talk to a doctor, they may feel like they're already out of time as puberty is already starting.

That's a fairly small number of cases as far as I'm aware, though yes, in principle if the child is already trans well before puberty starts, it would make sense that they'd want to start using them shortly before puberty starts. Of course, if we're discussing to what extent parents should let their children make their own medical decisions, it does indeed make a difference whether the child is 11 or 17... but, as far as I've seen, the attempts to ban blockers or other medical treatment tend to be for everyone below 18.