I may not be a "veteran" since I've only owned for a year, but best advice is going ahead and make the reservation as soon as you can. Change it later if you need to, but if you think you might want to go, make the ressie
We've only been DVC owners since '04, I would have to agree with Chelle in that if you think you want to make a reservation, just book it--- you can always cancel or change the date! Also, when in WDW, don't forget about all the discounts you can get as a DVC member!!