There is no right career path to becoming a product manager. If you are passionate about it, you will get there. I was a Software Engineer and wanted to become a Product Manager. I joined doodle.com, back then still an early stage startup. I was free to shape my role. I read a book called "Inspired: How to build Products, customers love". http://www.amazon.com/gp/aw/d/0981690408This was the best book on PM I ever read. I truly inspired me.

So my advice: join a startup or create your own. Don't join a consulting firm.