Wow annual pass / Diablo3 question

If you sign up for the Wow annual pass, do you actually have to pay for
twelve months before you're eligible for the free D3 download?

(and if not, how would they prevent people from signing up, getting the
free download, then cancelling?)

John Gordon A is for Amy, who fell down the stairs
gordon@xxxxxxxxx B is for Basil, assaulted by bears
-- Edward Gorey, "The Gashlycrumb Tinies"