Go online to babys r us. They will have a list of companies that will help you figure out which breast pump your insurance will pay for and they will file it for you. :) I did this kinda early that way I could put that brand of bottles, milk bags, etc on my baby registry. It was really easy. You just get your doctor to fax a prescription of a breast pump to them and they handle the rest. :)
I was told to call a month before your due date. And told that the doctor has to send some paperwork to the insurance company. But i have United healthcare