My 12 gig Mark II was fully loaded the first day I had it. It came in over my lunch break and I started copying all of my playlists right before I headed back for work. My directory structure on my computer was already set up like I wanted my playlists. I then spent the next several days tweaking things like song title that were longer than the ID3 tag would allow, and fixing the songs that I had forgotten to tag.

If you've already got things laid out the way you want them on your computer, it doesn't take long at all to get things ready to go.