I always run the ewe hoggs with this year's lambs, from when the youngest lamb is about two weeks old. It's a big help if the maidens have got used to young lambs before they're in the lambing field themselves. (Inexperienced gimmers can sometimes get a bit silly with all the hormones as lambs are being born, and I have had damage caused in the past, with gimmers charging about. Since I started putting the ewe hoggs in with the babies, I have had far fewer problems.)