I'm designing/building a niche product for file sharing. It's something I'm intimately familiar with and I feel like I have a good idea of where to go. I sent out a survey and got about 10 responses in the first couple days that confirmed my idea and gave me some new directions/competitors to look at. However, that leaves my mailing list at only 10 people. I've been sharing our landing page with an intro video, a product demo, and a beta access signup (offering free extra space and discounts on premium tiers) but haven't had much luck in the last week.
When do I stop trying to build the mailing list and start building? I've had a history of building products and being unable to find a fit or be unable to market it. This time feels different in that I know exactly what problem I am solving and for whom I am solving it for, but I'm trying to tread lightly. I'm a software engineer, so I'm trying not to jump the gun and do "the fun part" before it's time :)