You might want to have your boyfriend actively give positive association. Have him feed the bird the majority of the treats & such. Talk to him a lot. There is a strong possibility that he would dislike your boyfriend enough to attack and bite him. Especially if he bonds with you, considers you his mate and defends you like Rosco does with Tootsie. Though not the strongest bite among parrots he could bite hard enough to hurt and draw blood. I'd rather get bitten 10 times by Rosco rather than once by Sidney. He may be smaller but dang is his beak strong!
A mimic is good. I think Rosco first started with his favorite "Whatchyadoin?" at about 3 months. I would not consider less than a week too soon. Especially if he likes you and wants to get your attention. In my experience, Blue Crowns are clever. He is already learning about you, how you do things and what you say. I could put good money on it that whenever you are in sight, he is keeping an eye on you. And he might be starting to contact call when you go out of sight.
Don't be concerned about rubbing his beak like that. It is an instinctual thing to keep their beaks in condition. If he does not have any, I would recommend getting him some natural wood perches, maybe a cement type perch and a mineral block of some kind. More variety is better. Good wood & natural leather toys to chew on too. Tootsie's favorite is to rub her beak on a cement perch. It almost looks like it should be fingernails on a chalk board uncomfortable. Her beak ends up rough and scratched on the sides. But it is good for her. Blue Crowns can get a long and thin taper on the tip of the beak if they don't condition it enough. Tootsie used to be less enthused about maintaining her beak and it got too long and occasionally I'd find that I could easily snap the tip off with my fingers. Different perches in her home and she started maintaining it a lot better.
Thinking of the cage your bird is in and perches. Does it have rope or natural wood? A lot of people keep the perfectly round wooden dowels that come with cages. Those things are murder on a parrot's feet. It can cause them to become arthritic after a long time of always being in the same position. Tootsie had dowels when I first got her. My brother didn't realize any better. And honestly, I didn't either at that time. But a lot of reading on the internet and an earlier bird forum I belonged too set me straight on that. Still, her feet are not the best. But a lot of that was injury sometime in her past, a bad vet who broke a toe during an exam and just plain age.
