Dear student,

After every round of counselling, josaa will display the vacant seats left before every next round counselling on it's official site.
Also there is a seat matrix issued by josaa so that students get to know that how many seats are available in the institutes.

In some cases the closing ranks remains same for some branches, then that means there is no vacant seats left. But in either way, josaa will release list for number of vacant seats before commencement of each round counselling or seat allocation.

Check out the following link to know different dates of josaa counseling :-
https://engineering.careers360.com/articles/josaa-counselling