Potter had been the first one to go, being the ever-self-sacrificing Gryffindor he was. When Draco and Potter landed just outside the hedges surrounding the Manor grounds they had waited several long and desperate minutes. But each minute came and went without anyone, being any the wiser of Draco and Potter's presence. Meaning Draco's theory had been right. As long as he was the one to Apparate them inside the wards, they could circumvent them.