This is my "home page" in my browser. When the clock reads 0 days, 0 hours and 0 minutes, I'll "consider" seeing my dealer. No point (for me) until then.
http://www.dodgechallengercountdown.com/

Of course if you're willing to be gouged and have the money (say, MSRP + $10,000.00?), you could start visiting dealerships a few weeks before that.