You're smart to be looking into it now, as it's not uncommon for more popular weeks, resorts and room categories to "sell out" at 11 months.
I've rented through David's Vacation Rentals (3 times now), and more recently, rented points directly from a [verified, triple-checked, reputable, able-to-offer-me-a-written-contract] owner on the MouseOwners board. (*Note: You'll want to be careful with rentals directly from an owner, as you're not protected against the consequences of fraud to the extent you would be if you rented from David's or another reputable middleman: I wouldn't recommend direct points rental to someone new to renting DVC points.) The process has been seamless, and has saved us 20-50% off of rack rack rate (it varies: you save a higher percentage off rack rate with a studio or 2-bedroom than a 1-bedroom, and more at certain resorts than others, and more at certain times of year).
The main downside is that DVC reservations are non-refundable if you cancel (although my contract with the MouseOwners member allows me one "rescheduling" if there's a medical emergency or death in the family, which is nice). For this reason, we often get vacation insurance through TravelGuard to cover the non-refundable cost.