Employee Preview "should" happen this week, starting as early as today/tonight... keep an eye/ear out for anything. They know that once they say anything, word will spread faster than a California brush fire in the summer...
And yea, when it comes to the first soft opening day, don't expect it to be open all day. I wouldn't be surprised if they waited until the last two-three hours the park is open to let guests in. And of course, riding FJ or Hippo is not guaranteed....