When is the ripe time to buy New Nikon D7000 to get the best discount?

Nikon D7000 was launched in the last quarter of 2010, price varies from USD 1500-1800 for standard 18-105mm nikkor lens with full accessories.

Actually there's no best time because the makers, in my experience, never discount their gear.
Discounts are done by retailers both on and off line so you'll just have to watch places like
B&H in New York, Amazon and your local stores.