They met in 1942 and from then on (= starting at that tim) they were firm friends. 他们于1942年相识，从那时起就一直是好朋友。（《朗文当代高级英语辞典》第6版then）

        She left in 1984 and from then on he lived alone. 她于1984年离去，从那时起他便独自一人生活。 (《牛津高阶英汉双解词典》第9版 then)

       Please try to be more careful from now on (= starting from now) .  从现在开始请尽量加倍小心。（《朗文当代高级英语辞典》第6版now）

       From now on I'll be more careful . 从今以后，我会更加细心。 (《牛津高阶英汉双解词典》第9版 now)

       You must be more diligent from now on . 今后你要更努力。 (《英汉多功能词典》新编双解版now)