I am in the same boat... I just got off the phone with usps. The package came via EMS (china). All they keep telling me is 30-45 days to wait for a NOTICE! My package arrived on 12/20.
When I lived in Europe, you just go to the location and pay whatever duties or whatever.
Apparently, when you use dhl,fedex, etc, they have their own customs agents assigned and everything is taken care for you.
JFK Customs