Undescended teste?

my son's left testicle is undescended. He is now 6months and has his first follow up appointment since his birth in 2 days. They said if it's not down by the time he is 12months then they will need to surgically bring it down. It doesnt look as though it is coming down as yet. Has anyone's son had to have the operation? I really hope he doesnt need it, but do you think it will come down before a year is up?