YOU SAID:
How old were you when you started to read sentences
INTO JAPANESE
文章を読み始めたのは何歳のときですか
BACK INTO ENGLISH
How old were you when you started reading?
INTO JAPANESE
読み始めたのは何歳の時ですか?
BACK INTO ENGLISH
How old were you when you started reading?
That didn't even make that much sense in English.