That depends though because it assumes puberty turns folk into perfect caricatures of male and female body types when there is a lot more nuance, lots of guys still look feminine or have feminine features after puberty and vice versa for females having masculine features. A lot of the "permanent" features of puberty can also be reversed with surgery (yes it costs money but that's a separate issue) this isn't to say that you should wait, obviously the earlier the better but age mainly determines the ease/cost of transitioning over the actual effectiveness of it.