First, of all congratulations its the top most clg in india. There is not exact or correct date known to anyone as it depends on the vit vellore. The exact date that is to be xonsidered is only known when you get in touch qith the clg .

As on admission date you should ask about starting datr of ece

And also the lodge date of college hostel is two to three days earlier from starting date of vit . 

So my advice is to be in touch with vit vellore and refer their circular