For her, the dibels will show which letter sounds she knows and how well she can blend them into nonsense words. A first grade classroom generally has some VERY easy readers, books were you don't really have to be able to read at all because the pictures tell you what the words are, and she will most likely have "read to self" time when she'll be looking at books.
She may be more motivated to learn to read and move up to more challenging books when she sees what the other kids can do. Peer pressure can actually be a good thing. She might really take off with reading (one of mine did when switching from homeschooling to school because she wanted to be in the top of her class).
I always really like what Linda has to say.