I don't expect people to sit around and wait for a horde mission to launch before they do something about it. The hordie guys have to sit around planning the missions, forming the mission, gather the players, do all the dirty work, then when they launch there is a pretty large dar bar that shows up announcing that there is trouble coming.
Example. Last month. Minding my own business, most of the rooks were doing the same, just going about their day. I saw 2 dar bars launch way deep in the bad guys territory. So, since I was getting in some air time on the D9 I'll be flying in the scenario, I filled up the tank, grabbed a drop, and headed out there. I found a massive formation of bombers and escorts. This took about 40 minutes for me to get there. They were still 5 sectors out from our closest base. I announced heading and alt. No worries yet, just letting you all know type of thing. I paced them, kept updating the alt, heading, and now it was becoming clear what their target was. When it got close enough, the call went out to get ready and the rooks launched and intercepted the group. Slaughtered the attack, negligible damage to the targets, few bad guys made it home. Raid over, back to what everyone was doing.
Minimal interruption, got in some great furballs. It doesn't take much effort, but no effort will solve nothing. If someone simply doesn't want to do something about the horde, then the horde will simply continue on. Bloody their nose often enough, and the groupies will grow tired of it.