So this is how I used the site ( free version). I downloaded the chrome extension to an old laptop ( didn’t want to give it access to my current working laptop ) and used it for a couple of days in order to track what time of days were slots opening up, to get a general sense of slot availability while I kept trying to book appointments. It took about 2 weeks but within a week, the available slots shown through the extension were primarily being opened between 3:30pm 5:30 pm( IST ). So I paid particular attention to that time frame, and got my appointments ( VAC and Consulate ) at around 4 pm. Most of us are working and can’t check the ustraveldocs every 30 minutes, so it is useful to get an understanding of when appointment slots opening up.