I am a graduating senior in college studying computer science and machine learning. For the past year, I have been working with two other people on what we think is a pretty fantastic idea, offering a service to people that they didn't realize they needed.
We are almost to the point of having a working prototype (web/software).
Up until now, we have been very secretive about our idea. We've given some people a vague idea of what we're doing, but we're afraid of being too vocal about it because we don't want someone else stealing our idea.
At the same time, however, I feel like we should be getting the word out for marketing purposes and user-research to see if people will actually use the service. Of the few people with whom we've talked, everyone has been very enthusiastic and expressed a lot of interest, saying things like "I would have never thought of that, but that would be awesome to have".
In addition, I'm not sure when it is appropriate to start approaching investors (which I know nothing about). I think this is along the lines of the first half of the question, so I'll leave it here.
Thank you in advance for any guidance you can offer!
EDIT: Regarding the idea, it falls in the education/academics sector, and our anticipated revenue stream would come from colleges and universities.