The body weight will not change the weight on all four corners, unless the body has 500 lbs of filler on one of it's corners.
You want to adjust the weigh after the car is completely,..... finished. You can even really technical, by adding sand bag's (or the like) to the drivers weight or both seats if that's how the car will be driven most.
You can also do the same for wheel alignment. I do on my cobra, because of it's light weight. It DOES,.... make a different.