Start with a full length shaft. Use hot melt (carefully!) for your point insert, or wrap it in a layer of plastic wrap for testing. I would reccommend a point weight of 175 grains for testing.
This will give you a mid-range weight, that you may raise or lower to fine-tune later.
Shoot the shafts, noting flight characteristics. Ask questions here if you have trouble figuring it out. Slowly shorten your shafts by quarter inch increments until they shoot well for you out of your bow. I hope you have access to an arrow saw.
This may seem way too slow, maddeningly so, and can be frustrating. Just remember how much you spent on those shafts, though, and how many hours you worked to earn them. It takes many hours also, at least to start, to get them shooting correctly.
Killdeer