I had never heard the word ‘delta’ used that way before,@@@@@@@
Think military and mathematics. The “Delta” is the change from one value to another. When used in an op the Delta would be a new zero hour to kick things off.
WWG1WGA!
But for a designation of “Delta Squad” or Delta Force”, etc., it would mean a fourth in a series.
Alpha Squad
Beta Squad
Gamma Squad
Delta Squad
BTW...wasn’t Delta Force a TV show that starred Dennis Haybert?
Jobu!
If you were using radio, even encrypted, you would use a code not associated with time and then another code indicating the delay. E.G. 'Pogo Green I say again Pogo Green' As I write this I'm not a fan since we used to use 'Pogo' for a freq switch and colors for freqs. That was many years ago and we used it so much that way the commies have caught on. So it would be innocuous.