When to prepare the nursery

Hi Everyone, I've just been informed that I should expect a referral of a boy we're planning to adopt from Guatemala. It will most likely not be until next Spring before the adoption will be final and we'll be able to take the baby home. How soon before the baby's arrival should we be setting up the nursery? What about baby showers - do most people have them before or after the baby comes home? I'm new to this and would appreciate any advice. Michele