At the end of the day, lining up and knowing what you're doing is better than going up against a hurry up offense, then having to look to the sideline to see if the call changed, then running through your head what you're now supposed to do. Just set the defense and let them try to execute their assignments. When you have upperclassmen that understand the playbook inside and out, you can change the defense more.
As I've heard some coaches say in the past, "it doesn't matter if you're doing the wrong thing as long as everybody is doing the same wrong thing." In other words, you'll probably do a lot better if the defensive leaders just make a call and stick to it, even if it's the wrong one, than if you have a lot of confusion before the play starts.