Greetings Shashank!

Hope you're doing great.

That depends on the case of case basis. Some colleges may start their application process before the commercing date of examination of PGCET. However, most of the colleges start their application after the merit list and rank is being declared by the Karnataka Examination Authority(KEA).

I will suggest to check out the official website of the college you desire for admission on a regular basis for an update. 

Hope you'll find this useful. Do reach out in the comment section below if you need any help.

Cheers!