Hello,
Currently i am on H4 visa and got admission into masters for fall 2016.
So i am planning to apply for change of status to F1 .Could anyone tell me how much time it will take for COS to F1 or do i need to go to India for stamping.
Processing time could be 2-4 months. You can check the actual times on USCIS site for your processing center for form I-539.
Dates are pretty backlogged in India for stamping. So before going to India, take a look at the wait-times there.
If everything is delayed, then maybe you can enroll on H-4 and then move to F-1 from next semester when COS gets approved.