When the fast of the 17th of Tammuz begins, and ends, in Kew Gardens Hills, NY (2012)

According to MyZmanim (searching for 11367):

Fast Begins at 3:45 AM Dawn - Degrees or at 4:20 AM Dawn - Fixed Minutes Eating of a settled character - אכילת קבע - may not be started during the half hour immediately preceding dawn. Please consult your Rabbi for details.  Fast Ends       R' Tukaccinsky     The fast ends no later than the emergence of ג' כוכבים בינונים at -   9:05 PM       R' Moshe Feinstein     One who finds fasting difficult may eat at -   9:09 PM One who does not find fasting difficult should wait until the time for מוצאי שבת at -   9:18 PM [מהיכא תיתי]

Do not rely on zmanim times to the last moment.

And according to the Etz Chaim bulletin:

Fast of Shiv'ah Asar B'Tammuz Nidcheh begins at 4:20 AM

Fast ends at 9:11 PM