It might be earlier than you think. I found out a while ago that I watched my first anime at 8 years old. It was Voltron. I was surprised, but not shocked.
Others that I recently found out are anime:
Force five
Battle of the Planets
Warriors of the wind (AKA: Naussica:Valley of the Wind)
10 or 11 and it was Sailor Moon. But I was too young to really understand what it was. My sister and I used to make fun of it because it was "drawn funny."
I was 6 or seven, but the first anime I saw that I KNEW was anime, and not just like everyother saturday morning cartoon was Ninja Scroll when I was 12
6 to 8. Not exactly sure, but I saw a whole bunch sometime in that time period (Speed Racer, Robotech, Voltron, Transformers...)
The Birds are using humanity in order to throw something terrifying at this green pig. And then what happens to us all later, that’s simply not important to them…