I disagree, assuming a symmetrical system, he knows our deployment zone and roughly how large our deployment zone is, and he also knows he goes first. So that means he can move pretty freely until we get our first turn.Yeah, but he doesn't know we can't see him before he gives his orders. The battlefield distance during the start means the attacker almost always operates blind.
In-universe, he can advance without worry until his scout reports movement in our camp and on our side of the field. He was noted to have done a good job scouting us.