The sweet spot would have been to sell it, as soon as you bought it. I'm not being coy (well not too much
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
) but as you wait the price decreases. The closer you get to the rumored release of the new model the increase in supply and decrease in demand.
I've seen threads in the iPhone forum where people sell their phones a months, 2 months and even longer to maximize the price.
I usually sell my phone after I get the new one, and while that impacts the money I may get, it simplifies the whole transition process. If I were to get the new apple watch, I suspect I'd follow that methodology as well.
I'm not saying its the best approach but I do think the difference between selling something 1 month prior to release and 1 month post release will not break the bank. Just my $.02