I've done JFK to NYU Med (next to where I live) in 25 minutes and I've also done it in 2 hours. With 0 traffic 25 minutes is realistic (and what google maps says for the trip) but otherwise 45 mins - 1h is about right.
The traffic within Manhattan can be really bad in the morning. Luckily you are right next to the Holland tunnel but traffic can still be bad early in the morning all the way to Newark.