Temperature is really only HALF of the story. Humidity also plays a major role.
Here's some stuff that might help, Jack Frost/Big Boulder goes into a bit of detail in snowmaking.
http://www.jfbb.com/explore/snowmaking
Also, refer to this chart, anything below the "curve" is prime for snowmaking.
That being said, it's possible they could start making snow Wednesday night, but Thursday night looks a bit better (so they'll probably wait to turn the guns on), then they'd have to turn them off Friday during the day, and they could possibly make snow Saturday, Sunday, and Monday all day it looks like. So, it's unlikely they would open on the 10th, the 11th is possible depending on how much they can cover, but I'd say Tuesday or later is the best bet.