In general I reccommand to consider your interviewer as a client and yourslef as a consultant.
So basically you want ot share your note each time you feel it's needed for the good understanding of your oral message. Below the typical situations where to share notes but this could be done at other time as well :
- when explaining the initial structure
- when describing a value chain
- when synthetizing info. and findings of the case
- when moving to another section of your structure, especially if your were very deep in details before, getting back to your plan will help the interviewer follow the reasonning
Last but not least, if you have to share your notes, this means to make an effort to write as clearly as possible on your paper so it can be read easily by someone else.