Well, since I’ve passed my B.Tech degree an year ago & I also did crack the so called ‘placement season’ then, I think I’m quite qualified to answer this question.
Now according to me, you really don’t need 3–4 months of preparation for cracking the placements if you’ve already studied for writing the GATE exam. All you require is a couple of months & all you need is to put at least 4–6 hours of study judiciously everyday. Don’t worry, you’ll get plenty of time in the final year of your college to prepare as well as enjoy the last days of college. If by any chance you haven’t prepared for GATE, then you’ll need 3–4 months at most.
Before I tell you about what to prepare & how to prepare, I would want you’ll to know that maximum of your knowledge & hard work is only required to surpass the preliminary rounds. As you enter the GD & PI rounds, it’ll be only your smartness, wittiness, self confidence, & a bit of luck that’ll guide you towards achieving the first job of your life. As a rough estimate, it would be 50% smartness, 30% knowledge (as I’ve seen people with comparatively low technical prowess getting through) & 20% of luck (that makes a huge impact during placements & you’ll find that yourself the hard way) to finally put your name on the ‘list of selected students’.