I can't help you with bluffing because I've never had a bird that did it. If any of my birds offered to bite, he was being real serious about it
But, if I were you, I would not be trying to interact with them. It's too early, you just got them a couple of days ago and any attempt that results in one of them trying to bite is not recommended at this point in time as it's completely counteractive [it will only teach the bird to get its point across by biting]. Are these birds both DNA'd males? Because if they are a male/female pair, I doubt you will be able to handle them once they become sexually mature...