Have you checked Sensorly? Work in New York has already started.
Granted, most of the city still isn't covered, but it's a start, and you have to remember that work slowed down in the region because of Sandy. Yeah, it was a long time ago, but it still takes time to repair it and catch up with Network Vision.
Just because Sprint hasn't mentioned a city in its announcements doesn't mean LTE is completely unavailable. It just means they don't have what they consider adequate coverage yet.
If it isn't in your area yet, you may want to wait to upgrade to an LTE device, but Network Vision progress will probably speed up sooner rather than later, barring any terrible weather New York may experience this winter. Expect much improved LTE coverage in the coming months.
Oh, it won't finish in New York by January. Puerto Rico will be the first 100% complete market, and it's expected to finish in January. Chicago will most likely be the second 100% complete market, and it's not expected to finish until March, and New York will be a ways off still.
Now, that's not to say that coverage will still be terrible or that LTE will still be non-existent come March. In fact, there should be a noticeable improvement around the city in the next few months (if the production rate is anything like Chicago). But completion will take a long while still. New York is much too big to expect it to complete in just a couple months.