You really really don't need to dash the direction you want to moonwalk with Falcon. Matter of factly you don't need to do that with any character. At most you have to WALK the direction you want to moonwalk. Even that isn't Falcon. I go from standing to moonwalk every time.
And like Spak said, you should go from the notch below horizontal to the opposite horizontal making sure to go between down and neutral.
And like Spak said, you should go from the notch below horizontal to the opposite horizontal making sure to go between down and neutral.