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.
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 -
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 AMFast ends at 9:11 PM