It's up to Brovo but I think it would take a little more years to train, if he didn't have any bow skills or throwing skills it will take longer so it doesn't have to be when he was 18 could be 15 and still be chosen. , and the rangers choose their own apprentice. It's an elite force that is not just something to join and leave. Not everyone can just join. It will make sense for him to join if he was really skilled in sneaking. But again it's up to Brovo or tempest.

Just makes more logic to me but I do like the character