Hello dear aspirant ,

Hope you’re doing well …

Application process in university of delhi starts in may-june, just around the time when your 12th board is released.
admission in B.sc honours any subject is given on merit basis, no entrance for this course, basically in B.sc admission aggregate of PCM or PCB is taken into consideration.
application process is simple, fill the form, basic details, select courses of your interest, pay application fees. Application form submitted.

Then after a month of cbse result .. cut off is released and you can take admission in which ever college you meet the cut off.

For now, i suggest you to focus on your 12th and pay special attention to PCM or PCB

Hope this helps

Please ask if you have any more questions

All the best for your future!!