Hello Anitha. Thanks for contacting Careers360 and we hope we will be able to answer your query. 

I would first advice you to look at this Careers360 article for reference regarding counselling for postgraduate courses:

• https://engineering.careers360.com/articles/gate-counselling?amp

Summary: The qualified candidates of the post-graduation engineering entrance exam must know that there is no common counselling for GATE 2018. Candidates will have to apply for admission in M.Tech programmes through separate counselling conducted for GATE by institutes like IITs, NITs, IISc Bangalore, GFTIs and others. Institutes like IITs will conduct GATE 2018 counselling through Common Offer Acceptance Portal (COAP).

Also, please note that the registration dates are given in the link provided. 

Hope this helps you and all the best!