Most of your better breeders of Fila or also excellent trainers. They can get a lot more out of their dogs than the average owner or even the average trainer. We were able to meet most of her dogs. You could most definitely tell how uncomfortable they were but they were also very obedient and did whatever the breeder asked of them. This is unnatural for them and takes a ton of work.
I may take some flak here and I don't want a newbie to get the wrong idea but Filas are not blood thirsty, nasty dogs. Most are not going to chase you down the street and if given the chance they won't maul. They will warn with a bite and if you stop the aggressive behavior, the Fila should stand their ground and wait for their owner to take charge. Leave a Fila alone and don't come on his property and he will leave you alone.
Yes, it can take some time for the temperament to develop, most should have it by around one, some take a little longer. With our male it was obvious at 9 weeks he didn't like most people but would tolerate them by 9 months we stopped all contact with strangers.