Hi, My senegal is barely 4 months old so I can't comment on a senegal in particular. But I do have a 9 year old B&G.
One thing I did to 'deal' with his hormonal issues. I tried my darndest to make it clear I wasn't afraid of him. When he would get bitey, I would shove my thumb under my fingers and wrap my fingers around like a fist. That way he can't get my thumb, or my fingers. Then I would bend my wrist, hand down, like I was showing someone a nice watch I had on. I would present the back of hand to him without straightening my wrist or my fingers, and keep the thumb tucked. Even his big beak couldn't easily grip the skin on the back of my hand with it tightened (to help with that, I would keep moving my hand ever so slightly, like quarter of an inch, side to side, because given enough time, he could have grabbed a chunk of skin).
I had to make sure the back of the hand stayed in front of his beak or he could grab the side of my hand. Very quickly he learned that attempting to bite had zero effect. I could tell when he realized that because he would lean back, open his beak at me and stop trying to bite. Then I would move my hand down (thumb and fingers still tucked, back of hand up towards his beak) and have him step up, whether he wanted to or not. Eventually he would either step up (most of the time) or fly away. Either way he got the point that he isn't in charge (at least I think so). This I learned from a friend that had 12 birds of varying types.
Another thing I would do is lay my hand on his beak/nostril area. This was harder because it left my fingers open. But, it was nicely effective. I would hold my fingers and thumb together (like if you were tell someone to STOP), and hold them over his head and slowly move them closer. He would of course try to bite, I would move just far enough to get out of his range, and then move back in after the lunge. Generally I was then able to get my hand on the top of his beak, all the while telling him 'No Bite'. They can't move around to the side of your hand quick enough to get a hold of something, and with your hand on their beak they have a hard time moving backwards. It is kind of a passive way of getting physical control, without actually holding them. I do something similar when scolding my dogs, but rather put my finger on the top of their snout. The breeder of my Senegal does the same thing for her macaws.
I think it is important to not ignore the behavior, they are attempting to assert dominance, and if they are able to get you to do what they want, they may continue the behavior even later. Loki isn't a caged bird so I can't comment on what do if he is showing that inside the cage. But I would use the cage as a punishment, which I think is double bad for him because he is never inside of it normally. There will be blood sometimes, I gotta think that any long term bird owner has bled, sometimes you gotta just suck it up.

If he does get ahold of me I think shove my hand up into his chest rather than try to jerk away. He has always found that bit of reaction uncomfortable, it takes him off balance and his head doesn't really bend that way so he lets go. If you can get him to let go, any damage won't be as bad (hopefully). And yes it hurts, and goes against instinct, but really will help. Also if he grabs a finger, if you are quick enough you can grab the bottom beak with your thumb and "roll" your finger into his mouth, that way he can't grab it with the top beak and he may let go. This is harder to pull off and not always successful, but in a last ditch effort, not a bad way to go.
Of course, what worked for me, may not be effective for your birds, but don't give up trying! As young as your bird is, just keep working with them and there shouldn't be any lasting issues.
Mike