The NICU is a great way to break in your baby. Your baby will come home on a three hour schedule. Your baby will sleep through any kind of noise, up to and including the loudest barking dog you can imagine. Your baby will drink formula at any temperature, from any bottle or nipple, and will also breastfeed as long as you did that in the NICU, too. Your baby will be used to crying and not getting immediate attention. If you have a preemie, that crying will not be too loud or disconcerting, and it almost always means hunger, so there is no mystery to it.
And as a bonus, the NICU breaks in parents, too. When your baby comes home, you will already know how to take his temperature, feed him with breast or bottle, give him a bath, swaddle him, and change his diaper. You will also know his personality and how to read his signals.
Still, I don't recommend it.