Mine have free-ranged ever since they were 6 weeks old and were feathered enough to stay outdoors. They don't leave. They will fly around some but generally stay near the small pond and barn. They know where home is.
I wouldn't ever clip their wings, as size IS a problem with predators always on the look-out, and I feel better when they at least have some protection. My ducks free-range every day (expect when there is lots of snow on the ground) though predators have never bothered them yet. And we hope that this does not change.