I'm a first year UW student. Last year they called a lot of people on the first day. You will find out by phone. I was not called on the first day. In fact, I didn't hear until mid January. If you are rejected I would guess you'll find out in the next week or so by letter. But if you don't hear anything that is good news. You will either be ultimately accepted or you will be on the wait list. But I don't think you'll be outright rejected. Don't quote me on any of this... just my experience.
PS although they are nice I don't suggest you call them. You won't learn anything. I know it's hard, but hang in there.
Just thought I'd drop a line since it was so worrysome last year and remember you might not hear for weeks so try and just let it go for now.