Or you put it on a 5 min timer for testing - so it goes off shortly after server start? I don't use any admin panel so I don't know how that works - but you could get it to execute after 5 mins (sleep 300 at the top) and call it at the end of servermonitor.
This way nobody controls is, you can still test it, and it should run on all clients (you may need to call RE for some commands). This is how my airraid script works, and the animated heli crashes
If you have to use it through the tools, you can set a publicvariable and check it, have the admin panel set it to true when you want it to go off, and have the code have a waituntil (publicvar)
So how would I set the public var? Also, I tried calling it through the init.sqf, only to get the "Something went wrong" message. This is going to take a lot of work :/