It took me about two-three months to really start changing full steam. As for how long it'll take for things to settle down to some kind of stability? Years. It really is a long game and requires a whole lot of patience, which I myself sometimes find lacking.
As for BA, I'd say wait until they've stopped growing on their own since you don't probably want to fiddle with the booby-bits until they've matured. And you don't know if you even end up needing it, since you might grow good size ones naturally.