The problems you'll face if you leave it to the autumn to sell are two fold in my opinion:
1 Ducatis sell for the best money in May/June with low prices the only driver of sales as you approach winter.
2 The launch of the 999 replacement in November, if liked by the market, will drive 999 prices down even further, especially if Ducati give it 916 styling cues and introduce a 1100cc engine.