Bill Gross conducted a study of 125 companies in his portfolio and 125 outside companies to determine the top 5 factors for startup success. He found that while execution is important, timing may matter even more. His research showed that factors like market readiness, infrastructure, support services, competition, and the economy can significantly impact a startup's chances for success or failure. Entrepreneurs are advised to carefully consider questions about timing to ensure they enter the market at an optimal moment.