I too flew from the US, though i visited family and friends and stayed in India for a couple of weeks after the procedure.
I had expected them to begin work on the HT at 8 or 9 am on day 1. However, on day 1, they called me to the clinic at 4:00 pm. That day, they were only able to take pictures, make the headline, and make some slits. I left the clinic at around 9 pm.
On days 2 and 3, I was called to the clinic at 8 am and they worked on my head until around 7 or 8 pm on both days (with some breaks for lunch, etc. in between). I also requested to use the restroom several times during the procedure and they were very flexible with all that.
Hope that helps. Let me know if you have any other questions.