You can do it after.I have a question. Do we have to return our Indian passports before we apply for a Canadian one or we can do it after applying also? please advice.
If you are planning on applying for OCI, you can submit your surrender + OCI application together. Surrender application is to surrender your Indian passport and your citizenship. You will cease to be an Indian citizen once this happens. OCI is Overseas Citizenship of India (it is a multi-purpose life long visa to India).
The current process was posted by one of the members here!
Good luck!