Ready or not, school's a coming

So Olivia will be going to school in just a little over a month. We bought a backpack and a few other school things today. And I just don't want to let her go! I really think I'm going to have a hard time on that first day of school (okay, I know I am - it makes me sad already). I'm excited for her, too, but its such a huge marker of growing up. She won't always be my little girl who wants to wear the same white skirt every day and never get her hair done. She won't always want me to hold her when she's sad, have pink kitty parties, make such cute crayon drawings, play endless make-believe games with her brother, and wave to me every time she kicks the ball at soccer practice, and be sad after being at a friend's house for an afternoon because she "didn't get to play with Mom and Katelyn very much today."
I feel like she can't "get big" until I've learned how to be the best mom for her and had more moments of just playing and enjoying the moments instead of thinking of what other things I still need to get done, and developed more patience for her strong-willed self. (Okay, I know she's just starting school, I'm not losing her forever), but really, what is so great about full-day kindergarten?
We're planning on starting with half-day option (at her school you can switch to full-day anytime), but she's already saying she wants to do full day - I think she heard me talking about all the fun things they do in the afternoon.
I'll just miss having her around all the time and the fun that she brings (and I know her best friend Jackson will,too). I told John how I'm sad she can't stay little just how she is, and he said, "Yeah, but she'll always be Olivia." That helped - anyone else have any words of wisdom? (Maybe going to bed so my lack of sleep doesn't make me write sappy blog posts . . .)