Hi cortezabc,
First I completed the application form on this page -
https://portal3.passportindia.gov.in/Online/index.html
And then booked an appointment on this page -
https://www.vfsvisaservice.com/IHC-UK-A ... eUVLcp3A4=
It was not easy and it took me 2 weeks approx to finally get the appointment. There is no fixed time as such, I tried all possibilities, first I woke up at 12 am Friday exact, didn't get, then woke up at 6 am, didn't get it, 8 am no luck, then finally, at 10 am, I tried again, for Goswell centre, and it worked.
Also, I faced issues like once it took me to the next screen, it said enter valid e-mail address, even though I had entered a valid e-mail address. It turns out that my CAPS lock was on and the form can't take caps. So make sure when you enter your e-mail, it's in small case. Also, there might be some bug on the page like when you are supposed to click and select a date on the calendar, it does not respond and you have to again try? I don't know if this was a one off browser issue, but I faced it. In the end I managed to complete it using the latest Firefox browser.