We gave our kids peanut butter as soon as they were eating solid food. We live right next to the emergency room so we figured, let's just get it over with. Sounds like it's the right approach to introduce it as early as possible, anyway.
My wife is a dietitian and we gave our first daughter peanut butter (natural, no sugar added) starting at 6 months. The only other concern with PB is choking hazard, so we just spread it really thin on toast or crackers. At 6-9 months, they usually just suck on food or handle it. Rarely do they get a ton down anyways.
