Query related to Surrender of an Indian Passport & Applying OCI

Hi All,

Good Evening!

Thanks in advance,

I need your suggestions, My kid and I are British passport holders. We both have Indian Passports also. We need to surrender our Indian passport and apply for OCI.
Few things I am not sure about, whether I need to surrender my Indian Passport first and wait for the confirmation or Can I surrender the Indian passport and apply OCI the same day.
Please let me know.
One more thing, I am applying for my Kid also (four and half years old). Should I take him to the VFS ?

Final Question, Surrender and OCI timeline. 

Thanks once again.