I slightly disagree here, I would rather start with the Second Job or Phase 2, 'Hiring a Leadership Team and Making Sure They Work Well Together'. The more you focus on finding and setting up the best team early on the better. You can do yourself a prototype, write code or do market research to see if you are on the right track. However, I recommend to setup the founding or leadership team before anything else. Once you have the team in place the project gets momentum and pace will be 100x compared to before. And finding the team plus setting up all legal matters will be a full-time job your first weeks if not months.