Ours took 7 months, but others got theirs in a much more timely fashion, tho since yours is a resale, who knows how lonf DVD will take. Best to see if they can't get you a temporary card to use.
I called MS and they did say that it does take a while to get your card.
The person I spoke to said that your room key with DVC member on it will be all you need...I thought I read somewhere that you needed the members card to get some discounts?