Well i found that guy when it flashed up in my inbox that he had just broken the record for youngest portuguese premier division goalscorer. So i clicked on him and he was amazing as a 15 year old at Benfica.
But no matter how much I (was Real Madrid at the time) offered to buy him for....he just would not talk to me about a contract!
So i left him till he turned professional at 17 with Benfica and paid £12M to bring him to Real Madrid. While he was at Benfica he was getting fairly regular first team football.
In his first season at Madrid I played him 27 times, mostly from the bench but 12 starts. Which was about the same as what he had been getting at Benfica.
I then left Real Madrid for Arsenal and had to wait a further season to buy him from Real Madrid for £60M as an 18/19 year old.
From then on he has been my first choice striker! 160 goals in 132 appearances for Arsenal and only 21!
For i say around 25-30 first team games from 16 to 18 years old if you believe he's going to be amazing in a fairly strong league (in this case Portugal). From 18/19 on, feed him into the team till he becomes a regular starter by the time he is 19/20.
Also use a good training. I recomend this (i use the medium workload schedules):
http://www.fm-base.co.uk/forum/foot...ics-training/84281-duncs-training-fm2012.html
Hope that helps!