I hear this a lot and always say the same thing: if you can test your idea manually, without having to build any software, do it. There are so many great free software services out there nowadays and for most app ideas, you can string a couple services together or do part of it by hand to get everything going initially. Having real sales and usage will help you discover the things you couldn't have foreseen and understand your target user much better. Real sales/traction is also the best way to attract investors and technical co-founders.