I'm not planning to pre-order it or anything, but I will try to buy it soon after it comes out. I won't pay any kind of inflated prices for it or anything, so if it costs a lot due to lack of inventory, I'll wait until they release another batch and the price is made reasonable again.
I will probably read some review sites that I trust before making the purchase, but I think I'll ultimately end up buying the game, barring any major red flags telling me that it's horrible. Even then, maybe I should buy it as a collector's item, just like the CD-i Zelda games. They've become rare and valuable, despite how badly they are thought of as games.
I would say that SS may very well be the last major title for the Wii (at least in the United States), so it's probably best to buy it within a month or two of release. No later. Pre-ordering might be a good idea if you want to be sure you get a copy, but I don't think it's necessary.