The idiom, 'In the nick of time' means-

In the nick of time
English Meaning: at the last possible moment / only just in time.
Bangla Meaning: শেষ মুহূর্তে / সন্ধিক্ষণে

Example Sentence: We got there just in the nick of time.
Bangla Meaning: আমরা সেখানে একদম সময়মতো পৌছেছি।

অন্য অপশনে,
by fits and starts means- irregular
At a stretch means- without break.
by and by means- in no time.

Source: Cambridge Dictionary