Indian Passport Renewal for minor

Hi,

I hold British Passport and my wife is on Indian passport with ILR.

My son was born in India and he holds Indian passport with ILR.

My son's passport is expiring in few months. So I am keen on the list of documents required for renewing the same.

I was reading about the Non Acquisition of British Citizenship from Home Office. Is it required? If so what is the processing time for the same?

Any one applied recently please share their experiences.

Thanks and Regards,
Senthil