It would be a good idea to start writing all your ideas down, trying to develop it as much as you can before you hand it off to somebody else. It wouldn't have to be at all formal at this point. Also, a tip that was passed on to me, discipline yourself to always keep some kind of notebook with you at all times to jot down story ideas. Inspiration, for most people, is a totally unpredictable animal.
Bottom line; while you're finding a writer, try to get at least a broad outline of what you're looking for, especially the details that make it particularly interesting to you personally.
Best,