If you are asking the question, "when do I start branding".....the time has already arrived!
Assuming you have a viable business model (that should be your first priority), and a passion to bring your offering to the world, the branding process will focus your actions and set you up for success.
Something as "basic" as pricing, has huge implications for the perception of your brand. If you haven't begun the process, yet have set a price, you very well could be constraining your opportunity for success, or worse, creating a situation where you deliver conflicting messages to your market; a certain recipe for hard times.
Unless you have the most remarkable product in the world, that is easy to understand and solves a problem that has never had an answer (errr....a time machine perhaps), success is best achieved with a strategically crafted brand.
The sooner you have one to stand behind, the faster you can make contact with the outside world.