I started reading the Daily News when I was 8 years old, which was 6 years ago.
I've been reading the Daily News since I was 8. That was 6 years ago.
この場合、次のような言い方ができます。
ーI started reading the Daily News when I was 8 years old, which was 6 years ago.
「6年前、8歳の時にディリーニュースを読み始めました」
ーI've been reading the Daily News since I was 8. That was 6 years ago.
「8歳からデイリーニュースを読んでいます。それは6年前です」
ご参考まで！
カナダ 
