I do load testing while forming brass and shoot it at whatever velocity gives me a competitive load. I proceed to shoot matches with it until I get all my cases formed. Usually the forming loads are almost as precise as the fully formed loads and are usually within a grain of charge weight. My current comp load uses the exact same charge for forming as well as formed cases and shoot mighty well with both. Understand that I am not loading hot but moderate velocities for the bullets/cartridges used.
By the time I would be happy with my tune for new brass, I wouldn't need to have a tune for new brass.