Congrats! Nicaraguans are my favorite because of how spunky they can be.
Your husbandry sounds perfect. Your snake is just being a Nicaraguan boathey can be a little high strung and a little nippy and a little bipolar, but they will usually grow out of the nippiness with regular handling.
My nic was like that when I brought her home; for the first few feedings I literally had to turn off all the lights in the room except for one and freeze when she took the rat because otherwise she would see me and leave to rat to start freaking out on me. Now she's getting better with it, it just takes a little patience. She also used to just sit there in an s coil and watch me when I walked by, and I actually used a hook on her to get her out of the enclosure for the first couple months, but now I don't use it unless she looks pissy (because they're all a little schizo sometimes - all chill one minute, then freaked out the next)
Once your boa gets settled in it should calm down a fair bit. Just remember: regular handling is important to keep them hand tame.