It is probably just me but I believe you should get into Corporate world at the beginning of your career because it will make you realize some of things that you don't want :). But on a more serious note, corporate world will give you exposure to a lot of things that startups may not. For example, when you work in corporate world, you will learn about red tape, bureaucracies etc that will teach you a lot. You will get to meet tons of people working for big companies and you can actually build a really good network.

In really big corporate companies, you will learn how different teams use different tools, methodologies and you may have to work directly/indirectly with many tools, processes etc. In startups, probably not so much specially when the team is really small. For example, I saw at least 10 different systems just for project management when in my corporate job and I probably would never be able to compare each if not that exposure. I hated it but that's the point. Now I know :)

I worked in the corporate world for 10+ years before I went into the bootstrapped product mode. My best achievement in the corporate world ? The extensive network of amazing people I met during those years. And of course, I learned tons about what NOT to do when you have the power of running your own company (no matter how small)