I should add that the training needs to be done in a 360 degree arc from your loft for the total radius that you expect to do the wedding releases. After the young birds are experienced in flying around your loft, take them one mile in each of the four directions on successive days. Then increase to 2, 5, 10, 15, 30, 60 etc.
This will take more time than training for racing as the races are usually all run from the same direction.
Even after they know their way back, you should take them out a couple of times a week to keep them oriented.
You need to develop a method to call them in once they land, such as shaking a tin can with seed, whistling, or using fantails that you call in.