So I had my interview today (failed preliminary) and interestingly enough, they conducted all the interviews + aptitude test in one day. So everyone who went through the preliminary interview was told whether we passed or failed on the day itself. Those who passed went on to the panel interview and I'm guessing aptitude test thereafter.
Anyway, best of luck to all those who're going for the interviews. Be as prepared as you can be!
I did my homework but it just wasn't enough. I faltered on one of the questions which led to other connected questions.