phrase, idiomatic
to not let the opportunity slip; to seize the opportune moment; to lose no time
Examples (Wiktionary)
Mandarin
写作业了，竟发现圆规丢在了家里，自己真是一个大马哈，好在同桌看出来端倪，不失时机地递给我他的圆规……
寫作業了，竟發現圓規丟在了家裏，自己真是一個大馬哈，好在同桌看出來端倪，不失時機地遞給我他的圓規……
xiě zuò yè le ， jìng fā xiàn yuán guī diū zài le jiā lǐ ， zì jǐ zhēn shì yī ge dà mǎ hā ， hǎo zài tóng zhuō kàn chū lái duān ní ， bù shī shí jī de dì gěi wǒ tā de yuán guī ． ． ． ． ． ．
I was doing work when I realized that I left my compass at home. I am such a scatterbrain. Fortunately, my deskmate figured it out and lost no time in passing me his compass...