NYU has a (non-dorm) housing database that you can use as a student. Once you get your email log-in, you have access to it. There’s also good old craigslist.
If Wagner is located in the main downtown campus (near Washington Square Park) you’ll want to look for places off of any of the N,R,W, Q, 4, 5 or B, D, F, V trains. I’d check out neighborhoods in Queens like Astoria, Long Island City, and Jackson Heights. Or in Brooklyn: Park Slope South, Prospect Heights (be careful of places listed in PH that are really in Crown Heights), Prospect-Lefferts Gardens. Sunset Park is a good option if you find a place near an express stop (like 36th St.). In any neighborhood really, ideally you’d want a place near an express stop where you can also catch a couple of different train options. If you’re looking to live in Manhattan, places in upper Manhattan like Harlem are affordable, but the trains there don’t tend to run close to campus and often the commute can take longer than from one of the outer boroughs. There are also other neighborhoods you can look at like Williamsburg, Bushwick, and Bed-stuy, but I personally don’t tend to like them for various reasons. However, I know people who went to NYU who happily live there. And all of these suggestions are assuming that like me, you can’t afford to live in the Village near campus.
Since you’re moving so soon, you may want to sublet a place in the borough you’re interested in (Brooklyn or Queens or hey, Manhattan if you like) and use it as a crashpad while you look for something more permanent. Good luck.