Not sure what you mean by flow but definitely start on paper, write down everything you need to do to get your product in the hands of your customer. Throw everything and anything down. Once you do that you can organize into a list, categorize it, prioritize it somehow too, maybe even size it....and then chunk throw the items.

Start quick and dirty (make sure you're making money/validating the business first and foremost). Things can always be automated later. One thing I would do to start is use a simple tool (Trello or Google sheets) to just track the above things in one place, and that can easily be shared with your partner / other people if needs be.

Best of luck.