Surrendering Indian passport

Hi all,

My son is 2yrs old and he recently got his first British passport. Now I need to take an appointment to surrender his Indian passport and apply for a visa. My father is not well and I need to visit India asap that's why we will get his visa done and not OCI. Once we come back we will apply for an OCI card as it would take months.

Now my questions are -

1. We got an appointment on 28th November for surrendering his Indian passport. Now can we apply for his Indian visa prior to this date without having a surrender certificate?

2. How long does it take to receive the surrender certificate roughly.

3. What other options do we have to make an urgent VFS appointment to surrender the Indian passport? I can provide a doctor's certificate from India.

4. How long does it take to get an Indian visa?

It would be really very helpful if someone can help me with those questions, please.

Thank you.

Regards,
Prithviraj