The earlier you call, the more likely you will have to call AGAIN with flight changes (they do seem to happen a lot these days!)...I would call about 6 weeks before your arrival. I made ME reservations online several months before my upcoming trip and when I called to confirm, they told me that they couldn't "see" any reservations for people until about 40 days before their trip. So i re-submitted everything via email to DVC MEMBER SERVICES (we are DVC members), tags came about three weeks before our trip, and hopefully all will go smoothly next week!