I know this isn't the best answer but it really depends on what your product does. If your product is the kind of groundbreaking technology that the potential c

I know this isn't the best answer but it really depends on what your product does. If your product is the kind of groundbreaking technology that the potential customers will understand right away how it will impact their company (high efficiencies/lower costs/increased customers), then I would say demo the product...ONLY if the core functionality is built. If the main purpose of your product isn't working properly yet then you may want to hold off. If you anticipate that it might take the potential customer some time to fully comprehend how it will benefit their company, I would wait until you can polish the UI some more. A better designed and thought out UI will make it much easier for a potential client to understand the true benefit of your product. I know it's a little vague because I don't know exactly what it is you are building but I hope that helps