Only one reported regularly that MAY stamp passport EAD is JFK.
NOTE: K-1 is not a work visa, it is a fiancee visa for entry to the USA and marriage, K-1 is "Work Auth" primarily to be able to get the SSN, some states are strict in their interpretation of a federal law that requires persons applying for a "license" to have SSN, this can cause a problem with marriage license if only one person has SSN and the other (the K-1 holder) does not.
FAQ:
5.5)...Is there any way I can make absolutely, positively sure that my fiance(e) will receive work authorization so that they can go to work and help to pay the bills right away?A..No.
http://www.visajourney.com/faq/k1k2visa-enter.html#5.5Only marriage visas that guarantee work authorization upon entry to the USA are IR-1 and CR-1 Immigrant visas.