The first question I had above was about when the annual 5-night "started" posts. But that won't matter in the end.
Oh... ok. You get 5 nights when you open the card (mine posted before the card arrived in the mail).
Then you get 5 nights at the beginning of each calendar year. You don't need to wait for your anniversary.
The only thing that the anniversary date is relevant for is the $15k spend. You need to spend that in an anniversary year to get the cat 1-4 free night -- the counter resets to 0 at your anniversary.