Hello Aspirant, 

For checking the vacant seat matrix, you need to visit the official site of Central Seat Allocation Board (CSAB) on regular basis. They will publish and add a link soon for the vacant seat matrix. Currently there is a tentative seat matrix given on the site. You can check it here.

https://csab.nic.in/CMS/Handler/FileHandler.ashx?i=File&ii=141&iii=Y

Or this is the link to the official website.

https://csab.nic.in/cms/Public/Home.aspx

Hope it helped you..