We put our ram lambs in with adult rams and fleece wethers at 4 months, once last years lot have gone (our breed goes for slaughter at 16 months, so they have a whole year after separation until slaughter). We find that coming up to 4 months, the ram lambs start to get a bit feisty and too big for their boots. Suddenly finding themselves subject to the amorous advances of the older tups, they are put in their places fairly promptly. Any fighting between the young ones is sorted by the old boys. Usually it's just a gentle sideways shove, but if there's one which is aggressive, then the older boys are well able to chase them around the place, with the occasional headbut, until the pecking order settles. After that, all will be quiet, including when the stock rams return from tupping time