how much of your product roadmap do you share publicly before actually shipping?

​Sharing weekly progress and feature roadmaps on public forums creates incredible community excitement and gives us early validation before writing complex code. however, last month a larger competitor built a toned-down version of a feature we teased publicly weeks before our own release was ready for beta testing.

​how do you balance the momentum of building in public with protecting unique feature concepts until they are fully polished?