[alexdevkar]

If you are able to sell your product before it's ready, that is a great sign that you've found a customer's pain point. However, selling vapor-ware can be very hard. And you don't want to start your relationship with a customer with delays and buggy software.

Instead of pre-selling, consider talking to customers about what you're working on, having them take a look at the prototype and getting their feedback. You might not get the clear signal of a buy/no buy decision, but you will get help understanding what really matters in your product.

As always, depends on the particular business. Good luck!