You can travel to India on the Indian passport but will then need to surrender it there and get an exit permit (I think that's what its called).Thank you. Yes, postponing the ceremony is an option, sort of last resort. It's something I have waited for long, and now that I have an opportunity in hand, I do not want to push it further. That's why I am exploring all other possibilities before it comes down to pushing the ceremony.
The US option is technically feasible but I am not sure how it will impact your OCI application. They will be able to see that you used your Indian passport to enter and exit India while holding a Canadian passport.