Just booked Xiaomi Mi3 on Flipkart for dad! Sharing the snippet I used to book mine.
Use this snippet a minute before the booking period starts.
Run this snippet in your Browser Developer Tools Console on Xiaomi Mi3 page a minute or so before the booking period starts. This will send a HTTP request to book the phone every second.
How I got there? Answer is Chrome devtools - set breakpoints, read code and execute it in your console.
Chances are Flipkart will change their page for the next sale on 26th August. So don’t rely this. No harm keeping this running on another tab.