According to the top level page
http://www.freestateproject.org/ there are 9,034 folks who have signed the pledge so far, and 663 of them have notified the FSP that they have moved "early", i.e. they have already moved to NH since making the pledge. If I remember correctly I was #442. Or something like that. There are also a large crop of folks from within NH who subscribe to the same ideals, but as they were already here could not be counted as movers.
The bottom line of all of which being that, as you can see, there are already plenty of folks here to make a substantive difference, but that it will likely be some while yet before 20,000 is reached. I wouldn't worry about it: you can start working on following through with it as soon as you wish. As painful as some of the licensing procedures can be, and as much as we do fight against new licensing and regulation, New Hampshire government tends still to be pretty friendly and helpful about such things compared with many states. I would be surprised if you truly were put out of work for months by the licensing requirements. If you don't mind me asking, what is your profession?
Thanks for stopping by. We look forward to seeing you in NH!