I just reread your post and realized that you will be calling them in Tennesee in a nonhunted herd. Therefore the "bugle shy" bull theory may not apply to this herd. I have heard them answer a bugle as early as August, but for some really great action, go out the last 2 weeks in September and the first week of October and try your bugle as well as your cow call. I bet you will get some action and the bulls may actually come your way even with a bugle. It is just that in hunted herds, bulls learn fast that a man may be attached to that bugle sound.