I actually just wrote up a whole idea on the concept of introducing the Clan invasion on this thread.
http://mwomercs.com/...no/page__st__20
If you CBF, then basically my idea is this:
Space is large, and it takes a lot of time to get across it, even with FTL drives or whatever. Assuming that the planet/s we are fighting on in-game are not right at the forefront, or hell, even close to the edge of IS space, it'll still take a fair time for the combined forces of the Clans to invade, conquer, and transport their armies to each system. Months in-fact.
My proposal is that from this point out, for say, the next several months, we'll start hearing 'newsfeeds' and 'reports' from the outer rims, sporting outlandish claims of Clan attacks and invasions, with the actual invasion of our world being anywhere up to six months (or even more if the devs need the time) after the "first strike" of the invasion.
This will basically give the devs a good long time to really look at Clan tech, and conceptualize, design, manage, and finally implement it into the game fairly, whilst also keeping us tantalized with little sneak-peeks now and then.