Breast pump covered by insurance

So im in Canada. Ive emailed my insurance company (sunlife) and they told me breast pump is covered up to $300. I just need a written doctors referral. This may be a stupid question but does that mean I have to get the breast pump from a specific place like a pharmacy or can I just go to babies r us buy one and then provide them the receipt? And do I have to wait until the baby is born to buy it?