I think people should start studying English earlier in Japan.
I think it would be good for Japanese people to start learning English at an earlier age.
この場合、次のような言い方が自然で良いかと思います。
ーI think people should start studying English earlier in Japan.
「日本人はもっと早く英語を学び始めるべきだと思う」
ーI think it would be good for Japanese people to start learning English at an earlier age.
「日本人はもっと低年齢で英語を学び始めるのが良いと思う」
ご参考まで!