I doubt it, quite honestly. Each dealer has his own issues with surplus stock, fast moving stock, aging stock, OEM incentives, dealership inner bonus system incentives and so forth.
If something has been on the lot too long, you know he wants it gone. There's not nearly as much incentive to push out a hugely popular or harder to get model. Perhaps one of the many dealers on here can say something specific, but the best time to buy is when you, the customer need it and are ready to take possession.