The business model canvas is the easiest way to get a clear understanding of your who, what, where, when, and how. It does not need to be perfect, your best assumption will do. Once you have a first draft, your next objective will be to call as many potential customers and partners you can and test your assumptions. Each call will make incremental changes to your canvas. You will likely talk to 100+ people during this phase but will know you have something when prospective customers try to give you money to solve their problem. At that point you will come to people like me and say "I need 100k euro and will repay you in X-months with Y% interest (or business equity)".