it should be from the begining and probably the last 100 days 

Hi Bhaskar

I just want to update you that GATE is not an one year stuff as when you will see the syllabus for gate you will find that it contains stuffs from first year to final year. According to me the gate preparation starts from first day itself just follow the things what is taught and go through the type of questions that comes in GATE. If you start before even everyone begins u are ought to win. If even you are in other years start doing the weak concept and concept that comes frequently. This will help you a lot. 

Hopefully my answer helped

You should start from 3 rd year itself 

As gate is one of the most difficult exams in world .

The competition is cutthroat.

The earlier you start the better it is for you .

So visit this website for any information

Start from 2nd year. Gate syllabus contains all the subjects from second year. First year do the maths. Make the base stronger. Then from second year start the main preparation. First your syllabus then objectives maintain the time