I start all my rifles at about 25m. THis can reduce your time spent running back and forth to a target, and ensure you have a reasonable group on paper before finally testing your final distance.

Look at the balistics for the ammo you shoot and want to sight in, choose your zero yardage and then determine where the shot should be at the closer range. Some ammumition will actually be at zero on 25m and 100m, which makes this method very convienient. Alternatively, you could set your initial target at a distance that matches zero (for example if you want to zero at 200 yards, set the initial target at 30 yards to match).

Considering this post was a month ago, i'm assuming you've already completed the job but wanted to provide this info.