A proverb meaning you should act while the opportunity or momentum is there—strike while the iron is hot.
面接で好印象を持たれたら、すぐにフォローのメールを送った方がいい。鉄は熱いうちに打てだよ。
If you make a good impression in an interview, it's best to send a follow-up email right away. Strike while the iron is hot.
アイデアがまとまったら迷わず実行しよう。鉄は熱いうちに打て。
When you have an idea together, carry it out without hesitation. Strike while the iron is hot.
学生時代に学んだ知識はすぐに使って体得するのがいい。鉄は熱いうちに打てということだ。
It's good to use and internalize what you learned in school right away. It's the idea of striking while the iron is hot.