You should just plug the balls if you don't need them. Simply rip them off the stem (without damaging the stem of course).
You should always harvest your buds when more than 75% of the pistils have tuned red/copper/brown.
If you don't have any pistils or wanna be a pro about it, use a hand held microscope (of aprox 100x) to see the color of your trichomes. If more than 50% (that seems to be the preferred ratio for most growers) have turned from clear to amber of cloudy, it's time to harvest. But I have yet to see the pistil method go wrong.