The other part of your question (which is unasked, but still relevant) is what the timeline would be like on a resale.
Your sister should plan on 6-8 weeks from offer to fully closed and "in the system" and able to make reservations. That general guideline may in fact turn out to be less time, but it's best to plan for 6-8 weeks. Much of that time is waiting for Disney to make a ROFR decision, which can take up to 30 days. A second delay occurs after closing for Disney to receive all the documentation from the closing agent, set up the new account, and put the points in. That usually gets done in 7-10 days.
If your sister buys resale, it's unlikely they will be able to use their points for a reservation in June 2012. However, they could take a small part of what they save and rent a reservation from a DVC owner. In fact, if they're still in the research stage, that might be a smart strategy no matter how (or whether) they end up purchasing because it will relieve that pressure from a factor which really shouldn't be a factor in their decision.