Some experience from dealing with this recently: Unless you have a very large design team and long timelines, it's best to start with an existing design system and tweak it. Adjust it to your liking, get buy-in, and then agree to keep it locked in place except for minor adjustments. Save the big goals for a V2 design to be launched at a later date.<p>A design system is only as valuable as the time it saves. If the design team spends months perfecting a design system and associated sandbox demo before they can even get to the core design work, it's unlikely that it's actually helping deliver the product on time.<p>It's also dangerous to let the design system become a moving target, where the design language changes from week to week. Each change will burn developer time integrating the changes, which will inevitably turn into multiple sprints dedicated to creating a theming system for your products, none of which really moves the product forward.<p>In a true startup environment, if you can't get the design system 90% complete in the first week or two, it's at risk of becoming more of a liability than a benefit.