What is the minimum time in which the puzzles from reasoning section should be solved??

It depends on how many questions you are planning to attempt/ how much you are planning to score.

5 questions will be asked for each puzzle.
So if you are planning to attempt 60 -65 questions then try to solve within 5-6mins max.
If you want to attempt 85+ then you have to be able to solve the puzzle and answer all the five questions in under 5 mins(preferably 4mins).