Hello dear,. 

Orientation program in Delhi University is just a program which is conducted in the college for every department separately so that the the students who have been admitted in the college newly in the fresh year, can be briefed about their courses, faculty and syllabus..

No, the orientation program doesn't indicate the beginning of the classes. It is just for the students to make them familiar with the college rules and regulations and the aspects they will learn in the college and about the societies functioning in the college. 

Hope this helped  

Good luck!