Michael Schoch, Answers questions on Noodle
That's a great question. You should read this article about helping your child adapt to the school bus.
There are advantages and disadvantages to riding the bus, but if you plan on having your child use school transportation the majority of the time you may want to start acclimating her to the process from the very beginning. Instead of driving her, you could let your child take the bus and then follow behind in your car. When your child arrives at school you can be there to greet and reassure her so that she feels supported. This way you are still involved, but you're also giving her the opportunity to adapt.
For more advice and ideas, check out Noodle's Adjusting to Preschool page.
Best of luck starting school! Enjoy the rest of your summer.