It really depends on the dog - but if it was me I'd make sure I had the dog long before the baby was born, so the dog would be settled in and any necessary adjustments in my lifestyle were made before the baby came along and I had to make more adjustments. It would be terribly stressful to have a new dog and a new baby at the same time - and I'm afraid the dog might end up being asked to find another place to stay if your friend isn't prepared for all the new responsibility.