思い立ったが吉日

おもいたったがきちじつ · also おもいたったがきちにち

the best time for doing something is as soon as you've thought of it; there's no time like the present; it's an auspicious day (for doing it) when you've just had the idea

Meaning

exp
the best time for doing something is as soon as you've thought of it; there's no time like the present; it's an auspicious day (for doing it) when you've just had the idea

Example sentences

思い立ったが吉日、さっそくプロジェクトの企画案を書き始めよう。

Quick, let's get started on the project proposal while the idea is still fresh in our minds. There's no time like the present.
思い立ったが吉日！

Tomorrow never comes.