It won’t happen.
I think a lot of young artists are afraid that if they use up their good ideas before they’re ready to execute them properly, that they will fail with them and have nothing to replace them.
They very well might fail with their first ideas; that’s part of growth. But they won’t fail to have more ideas.
Ideas are ubiquitous. Good, bad, in-between: use one and another three grow in its place.
Don’t let the fear of running out keep you from starting. Take the idea you think is your very best and act on it today. Compose that song, shoot that film, write that short story.