Carlos, This is purely a matter of opinion. I can show you a few different references, but here's the short version of what you will hear.
Conservative - follow what the manual says. Get out for a few long rides and you'll be at 1000mi in no time. Kawasaki knows their engine better than anyone.
Aggressive - screw break in! Ride it hard! Open it up! Work the gears, because that will give you better power in the long run according to (insert website here)! Live it up!
In Between - for the first 500 miles, ride like you normally would for the most part, but don't spend any long periods above 6k. After 500, gradually push that limit upwards and, after 1000, no biggie.
I went with option 3. Didn't spend any long stints above 6k, but opened it up every now and then after 500 mi. This option was backed by the most reputable sources I could find, as well as most riders I know who keep their bikes long term, and thus care about longevity.