Some say that to be a successful entrepreneur you have to know when it's time to move on. While I agree with the statement, it's rather unhelpful - what that hell does it mean?

First, moving on does not mean giving up. Moving on means finding a different idea to commercialize, where as giving up means quitting entrepreneurship altogether to find the four letter word,"WORK."

For an early stage company, the real question is how do you move on when you're out of resources? The truth is you need to hedge the risk of failure from the beginning by planning for failure.

Real World Example
By nature, I'm paranoid. People say successful entrepreneurs are confident, not paranoid. Maybe I'm not the best entrepreneur, but my imperfections save my team. When we launched operations, we had exactly 6 months to zero cash. So, at the end of the day when I couldn't find anything else company related to invest my time in I began exploring markets for quick cash flow positive products we could commercialize in case things didn't work out as well as my co-founder knew they would. After exploring several products, we eventually settled on one, surveyed the market, found market interest, built a prototype and then started making connections. When shit did hit the fan two months later, we looked back on our risk hedging strategy with pride; if it hadn't been for my paranoia we would have been in the job market looking for "WORK."