Ask your local game retailers for most accurate info... I think Sunday morning is when they release them at toys-r-us, before the store normally opens.
On the plus side, Nintendo doesn't do much stock piling, (mostly move shipments around), but they are likely doing at least a little for Brawl... It will probably be easier to get a wii the week of release, but demand will likely be higher too...
Some store may let you pay in advance to reserve a wii from the next shipment.
There is also an aplet that will watch Amazon and fireoff all sorts of alarms when they get one in stock. You only have minutes (or less) before they are sold out though....








