At the end of the manufacturer fiscal year, but it's not necessarily the case. They have big sales throughout the year. Discounts may come after the new model year if they had a bad year and need to clear out the prior year model.
But the dealer is not offering a big dealer discounts at the end of the manufacturer's fiscal year. The dealer may offer increased dealer discounts where he's having a good month and has qualified for additional dealer incentives from the manufacturer for volumes sold, but especially if he is just shy of hitting that incentive at the end of the month.