I like when he start his career younger cause you don't have to compress his years as Robin so much and gives him more experience.

What age he was in Robin Year One, i don't remember they saying it. But by the looks i think he was around 10 to 12 and to me is the perfect window for him to start as Robin.

Eight years old is too young imo, but i would not be against Bruce taking him over around that age and training like two years to become Robin.