Think you're ready to start up? Put yourself to the test. Check out the five crucial keys to knowing it's time. Andy Palmer has started at least five companies by my count--and I’d guess he has invested in dozens of others. Based on that experience, I’d consider him an expert when it comes to deciding whether you have what it takes to be an entrepreneur. After graduating from Bowdoin with a major in English, History, and Computer Science, the passionate Rugby player was injured and decided to become serious about a career. So he got an MBA from Dartmouth’s Tuck School. From there, Palmer went on to be part of the founding team of five start-ups: Austin’s Trilogy; pcOrder.com, a Trilogy spinoff for buying PCs and software online, that was spun back in; Bowstreet, a “portal-based tool provider,” that IBM acquired in 2006, Infinity Pharmaceuticals, a cancer drug developer that went public 2000; and Vertica Systems, a database company that Hewlett Packard bought in 2011.…