I drive an Isuzu Kb300 TDi intercoolled turbo diesel (sounds so cool to say that) Mine was only really driven in properly at about 20000km. She is now on 66000km and she gets better all the time. I would say 2500km minimum to be safe. It will be beneficial to your engine in the long run to "baby" the engine as long as possible. I never used to go over 2600 rpm for the first 2500km. But I am talking about an Isuzu, I am going to buy a Sorento soon.