Op, and I love the name too, I have various friends who have become priests, tried an wd decided it wasn't for them, or succeeded.
All if them are successful in whatever they have ended up being, priest, nun, teacher, lecturer, lawyer, professor , etc. There is much less stigma now in leaving and people are less screwed up.about it than on previous generations.
The friends who did leave just did the " well it wasn't for me" and then got a qualification and did what they did. So I would worry I know, but actually they were fine.
I still think it is more sensible to pot off the decision until you are at least 21 or through university, but for sone people, as I say, they know right from the beginning. If they do, then it is cruel to prevent them and the important thing is to support them to make the right choices in that decision and be there to pick up the pieces if necessary.
Her family and I had to do that for my friend, when the first choice was not right, although it had been her long term plan. But, dv, this one is. We'll still be there if she ever wants out, as we were for another friend but we support her there.