Telling people your plans too early doesn't make you less likely to achieve them.  I know when I tell people what I plan to do the response I get most of the time is that I have to go back to the drawing board and find a better idea, that I still have a lot of work to do, and that the world doesn't need what I want to make.

Hardly endorphin-inducing excitement from the congratulations of well-wishers.

What concerns me even more though is premature over-exposure to a project.  If a project tries to attract and and foster too-large a community from the beginning, you lose a lot of people who have had a so-so experience, because the project isn't developed enough yet to support them all.

However, if a community is built from the ground up, person by person, organically, who then go on and advocate on behalf of the community, while the project continues to be developed and improved upon, that'a a much more sustainable model for growth.