Tony,
Try them full length before you cut, the calculator will get you close, you can fine tune once you have the head weight where you want it. Its easier to change the tip weight and change the center cut first and then cut your arrows if necessary.
Remember that everything that you add or take off will effect the flight, this included string silencers, brace height, feathers, etc.
I found that if I compare bare shaft to fletched shafts first, i know if i am close. Once both types of arrows group togeather I switch to fletched arrows with field point and broadheads.