Spend at least a few days in the Acclimatization of huaraz before beginning the Huayhuash circuit. This is very important, as the trail reaches an elevation of some 4300 metres within a few hours of leaving Llamac. In addition to a day wandering around town, I’d suggest doing a couple of short hikes to Laguna Churup (4450 m) and Laguna 69 (4600 m).