Nobody can answer that.
It's going to be a while. Until supply exceeds demand.
Update: not sure why someone said "Christmas" but I'd say closer to a month. Also MSRP was $380 not $350 ($450 for Founders Edition).
Real pricing probably won't drop below $420USD for quite a while for any model.
MSRP is only a suggestion hence the acronym. Just like AMD's $200 cards will likely start at $220 or $230.