to my understanding delayed eta units are invisible untill the delay ends and they start to move (or so says a thread that I can find)

so
If alliance A and alliance B were at war and alliance A maneged to gate troops into alliance Bs hive but had 3 ticks untill attacks hit

Could alliance A launch an attack at a player with a delayed eta of say 25 have the troops sitting there invisible untill the counterattack troops move back to the frontline and then procede to a massive sneak attack? from the outpost that had been captured shorty after launch?

They can also scan the outpost you are delayed from, and see you are there.