strike while the iron is hot; make haste when the path is clear
Proverb encouraging immediate action when one is certain of the right course. Often contrasted with 悪は延べよ (postpone bad deeds).
See also: 悪は延べよ
If a good idea comes to mind, strike while the iron is hot and start right away.
善は急げと言うから、迷わずに申し込んだ。
They say 'make haste when the path is clear,' so I applied without hesitation.