Most estimates I've heard for the number who've moved but never signed up run around 200-500, and a few have suggested maybe more. I've run into people who moved after hearing of the FSP while campaigning both in Manch and Seabrook, so it's plausible that over a thousand have moved that we don't know about or didn't sign up.
For that matter, maybe we need to call Next 1,000 the Third Thou'.
Seriously, the Next 1,000 needs support from folks. Call up radio stations, write letters to the editor, email your friends, and remind folks who are about to move (or have just moved) that this is a worthwhile effort. These two counters are critical to getting new folks to move in. Many have sat on the fence and simply declared this project hopeless. Others sign on for the 20,000 SOI, but then lose interest as the Main Counter slowly creeps up.
If we want to see this caravan effort work, we have to build up the groundwork and get people to commit to the move--by September of next year.