Its a sign that you need to put that snake down and let it acclimate.
You stated you knew it needs a week but have been handling it since day two, feeding early, etc.
The stress of overhandling a snake, especially a young snake is cumulative.
I don't handle new snakes till they've taken about 4 feeds. That snakes whole world has been upended, sounds like you are doing research, so why aren't you following it?
Let it shed, let it acclimate, and let it get another 3 feeds in... then start with small handling sessions.
Your snake has a very limited range of communications, hissing is one of them.
The snake's need for security should supercede your desire to play with it.
Bruce









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