The problem is that when an idea is in the embryonic stage it's often difficult to pin the central elements down that may be protectable. As you allude to, when

The problem is that when an idea is in the embryonic stage it's often difficult to pin the central elements down that may be protectable. As you allude to, when you have something tangible like code then you are in a much stronger position. It may not be too late for your ideas, but by the same token you may not actually have anything to protect. On a wider point, much depends on what your new employer will think of the fact you are working on side-projects that may compete with its own ideas. Regardless of who came up with the idea first, they may not want a new hire to be working on similar projects when their energy could be directed at the company's own similar project. Of course they may be perfectly happy for you to continue but it's of course vital you properly map out that work done on your own time will not belong to the company. In this regard, as the other poster says, you would be well-advised to speak with a local lawyer.