Well I struggle with in and stage.
The actor gave his speach from the stage
The crowd moved across the stage
I sat on the stage
At what stage of the plan are we at
we should stage a reconstruction
so no, I can't find an in and I'm not sure what the "steps" remark is about
Thinking further, if you consider a project plan where you have steps or stages you could argue that you are in a stage of the project, but that is pretty odd and most people would talk about steps or elements of a project.
What examples of in and stage do you have?