Hello there. I'm going by the YBR125 service schedule here, so I'm not too sure if the YZF is the same. I had my original at 600, then another at 1,000 and now I've literally just hit 2,000 miles and is booked in for it's third service on Monday. As the bike you have has had a new engine, I think the services are to clear out filters/clear out the gearbox debris and such.
-Tom