This is an old thread. The hardness of parmesan.
Reading up on large 100 lb parmesan wheels they age and lose approximately 17% of their moisture. So when I make it, and I've made it 15 times, it can age for a few months in the cheese cave. When it has lost 17% of its moisture, then either wax it or vacuum pack it. This worked well for me and I make 4 gallon batches.
I prefer the parmesan to be softer for easier shredding/grating. For this, I dry it for a week or so, then wax or vacuum pack it. The only issue with this 'wetter' parmesan is that it will mold easier too, so keep it frozen or in the refrigerator after shredding/grating if you do it in advance of using it.