I'm a rare bird in that I often book spur-of-the-moment, short-term planning trips for my DVC. Not disagreeing with everyone above - they're basically right, but the short term planning can be done for DVCers. Just not the way the OP was looking for.
Because I live only a 3 hour drive away, I find myself booking trips to Disney with as little as 1 month notice. In fact, just booked a trip for June 3-6 a few weeks ago. The difference is: I don't try that trick during event weeks, high demand times, holiday periods, etc. I mostly take these trips during the cheapest point seasons, and slowest park weeks. When I want to head up for Christmas season, Food & Wine, Thanksgiving, etc...those I plan as far in advance as I can. I also have extreme flexibility when I take these short notice spontaneous trips; I may check on availability at a resort I want, but basically I'll take whatever they got. I may want Boardwalk view at my home resort, but if a studio at SSR is all that's available...I'll take it. I've even split stays several times - moving from a studio at OKW for 2 nights to a studio at SSR for 1 additional night. I'm single, I'm either alone or traveling with a friend, and I pack light - so even moving around is something I can handle and accept, given the extreme short notice I'm exercising.
That doesn't mean not to try - you can waitlist, or call and hope to get lucky. But I wouldn't buy into DVC if my vacations were always likely to be short-notice, short-planning trips during high-occupancy event weeks or holiday weeks. That's not likely to work out vey well!