Good job mom! Keep up the good work and she will have a great time being the star of her class. Great confidence building and reinforcement for inspiring a drive to succeed. In the 3rd grade they are given the choice to test for advanced/accelerated classes. We call it the "ALPS" program in our state. If you don't have this, seriously learn about and consider homeschooling. (My son, refused to take the test. Now, in the 6th grade he's begging to because he's seriously bored. Now, it's a lot harder to get him where he should be. Ugh. ) Just try not to lose your drive (sometimes things happen -like a hostile divorce, double ugh), and she'll have a lot to feel proud of herself for.
I worked with my sons like you, still do. My sons were born in July and August (oldest). I started my oldest at 4. My youngest I held back so he started late. Both are excelling excellently. My oldest was doing simple algebra at 3. He is brilliant and he is quite a handfull as a result. My youngest was mildly special ed, but because I held him back it gave him confidence to far exceed all expectations; he never gets discouraged and never stops striving to be better. Both love school.
Extra advice: If your brilliant daughter's grades ever start to falter, nipp it immediately and not a week later. Make an appointment with her teacher and stay on top, everyday. One of my sons teachers said I was "one of those" parents that had too high expectations that was causing my son undue burdens and that I should be more realistic about his capabilities. (He was bored stiff). It was a little late to have him removed from her class, but she got the message and started helping to bring his grades back up to his capabilities, which is -all "A"s. You know your daughter, don't let anyone else mess with you or her future.
Have fun mom, enjoy your blessing.
Addition:
@lolo: I'd love to know what state, city, and school district you work for. I'd could consider moving. We don't have that in Michigan. Wish we did, it sounds excellent.