I would think, especially if you're going high with those llamas, that the bulls will be starting to try putting together herds. Might not be real vocal yet, but I think they will start taking an interest in the girls. I was out in Rocky Mountain National Park two years ago in late August and all the cow herds had some bulls with them already. Even some bugling going on.
I will be hunting later, but if I were you going early I would use cow calls and lots of patience. The bulls may very well respond, but very likely will be coming in silent and slow. Give it time to work. And most of all, have a great hunt! Sounds like you have a good adventure planned. Be sure to bring back stories and pics for us all!