So in the ideal world it should be done before launching. In reality a lot of brands skip / don't do this is throughly. There is the mentality "I want this" or "there is a gap in the market". Next to that no plan survives impact, so what you thought based on the research and what you see can vary. That is where indeed learning by driving demand can be really insightful and getting feedback: is the product / service you are offering actually providing the solution you hoped it would to the problem those customers are facing.