Parents are often given a barrage of different information as to when to start feeding our babies, what to start feeding our babies, and how to start feeding our babies. Research in the last few years has shown that introducing foods thought to be common allergens, such as peanuts and eggs, earlier in life may actually help prevent food allergies. In fact, studies have found that cultures and communities that introduce these foods earlier have lower prevalence of food allergies in children. I would still recommend starting with the typical rice cereal at 4-6 months for most babies. But in most babies, no need to delay the introduction of eggs and peanuts. Recently, The Wall Street Journal published a great article on this. For a more scientific read, the Journal of Allergy and Clinical Immunology, provides a more detailed review of specific studies.
Note that if your child already has food allergies, then food introduction should be carefully guided based on current food allergies, cross-reactant allergens, and severity of allergic reaction and this should be guided by your allergist or pediatrician.