Blastoff time, 8 letters
Commencement of hostilities, 8 letters
Critical time, 8 letters
Decision time, 8 letters
Military operation's start, 8 letters
Moment of attack, 8 letters
Moment of truth, 8 letters
Operation's start, 8 letters
Time of action, 8 letters
Time to attack, 8 letters
When an attack is scheduled to start, 8 letters