Use Hyper triggers and death counts
Check the wiki for both.
Hyper triggers makes the triggers run at 12 (really every 84 ms) times per real second on fastest, so if you want a "wait 15000", you need to convert into triggers. Since you want 15000 ms, and you have 1 trigger = 84 ms, divide by 84 to get 178.5 or 179 triggers. Now, you can set up a death count to start the "timer".
There are two ways to do this. You can count up, or count down. Personally, I think counting down is best, but ymmv. To count down, put a condition in your trigger for 0 deaths of some unit, and in the action, set that to some value (like 179 for 15 seconds). Have a second trigger which always subtracts 1 from that death.
To count up, it's just the opposite. Put a condition in the trigger for 179 deaths of some unit, and in the action, set it to 0. Have a second trigger which always adds 1 to that death (you can put a cap on it if you want, but there's not much reason.)
In both your triggers, you'll need quite a few to get them to work properly. Alas, this is starcraft.
colliderCP commands at least 1 men
CP commands at most 24 defilers
CP deaths unit1 exactly 0
set deaths unit1 179
set deaths unit2 1
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CP deaths unit1 exactly 0
CP deaths unit2 exactly 1
create 1 defiler at 'p1grab' for CP
set deaths unit2 0
exampleCP commands at least 1 alexei
CP brings at least 1 scout to 'build zone'
CP deaths unit3 exactly 0
kill 1 scout at anywhere for CP
create 3 ghosts at 'characterfollow' for CP
set deaths unit3 42
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CP deaths unit3 exactly 0
remove all ghosts for CP
Note you can only use that second trigger for the second one if you only control ghosts at that time (for 3500 seconds). You could technically set the CP deaths unit3 exactly 1, and then it would only fire once, but you would only have the ghosts for 3.4 seconds or so, not 3.5.
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