Just want to add to this. I didn't buy enough for my house to qualify for the free blow in machine when I did my attic. I wasnt going to pay to rent one either. If you are doing an attic you can actually use a rake to fluff it. Takes longer but it does work.

I did this in September as well as air sealing, reacaulking, spray foaming holes, and re weather stripping anything I could find leaking air around my 1942 house. Even though the walls are uninsulated my house held 70° last night and the furnace actually was turning off for a few minutes in between cycles.