Move them one stack per impulse, starting with your first impulse. So after your first impulse, the bulk of your units will still be off board.
I think you could declare that a leader has activated several adjacent stacks and move them all in one impulse if you like, though. In that case they'd have to have started out adjacent (though off board) like you say.
This isn't an official ruling, of course, it's just my best guess
[ April 30, 2003, 17:36: Message edited by: Bamse ]