That's great news! You were lucky, and others should be careful not expect to be able to get a MagicBand during their first trip when activating their APs. I am told they keep a limited supply on-hand of complimentary bands at MK, but these are not intended to serve every new annual passholder, so if they're out then they're out. Still, it doesn't hurt to ask!
Are you staying on-site at a Disney-operated resort? If so, then your MagicBands are included regardless of whether you have regular passes, APs, or even no park tickets at all. They usually don't ship right away, but should arrive at least a week before your check-in date.