Should I buy the gear now or wait until it's needed?

When the baby's first born the only things I'll need are the bouncer,swing, and carseat. I'm going to get the car seat/stroller combo. I want to get a jumper and stationary walker. Should I go ahead and get them if I don't get them at the baby shower or should I wait until the baby's ready to use them to get them? Also, what's the smallest size of clothing I should get? I was told not to get newborn, because the baby grows out of it too fast.