Hii dear, 

Firstly, Congratulations for making upto Delhi University. 

According to the official notification from the Delhi University site,, most probably the classes will commence from 21th of July for all the courses and colleges. 

Since this time due to elections  there was delay in admission process and releasing of cut off lists,, that is why classes will commence lately.

Previous year classes started from 9th of July only. But this time its quiet late..

Hope this helped. 

Good luck!