When a product is just new to the market is not the best economic time to buy. That is when demand is at its highest and supply at its lowest and prices at their highest. When supply has satisfied bent up demand is the best time to buy. When D800's (or whatever the next one is going to be called) are on offer at nearly every corner camera shop is the best time to cut a deal on one. Then, or near the end of its product cycle.
But then again, not every purchase decision is based on sound economic principles. If your heart is early set on one, or your needs can't be met otherwise, then buy when you can.
Remember, these things are not investments, they are depreciating assets. My main source of income is not from taking pictures, therefore I tend to be a bit cautious when purchasing these toys and buy them when the timing is right. Does not mean I won't get what I want, but I'll be reasonable as to when I get it. My retirement funds, my kid's education fund and my standby operating funds are way more important to me than getting the latest toys at their highest prices.