There is no need to delay the introduction of solid food in the hope that it may reduce allergies later on. In fact, it has now been shown that introducing cooked egg by 9 months and peanut-containing food by 12 months can reduce allergy risk.
Infants from 4 months on will start to display a developmental readiness and interest in solid food. Each child will be slightly different in timing but all should be ready for solids by 6 months of age.
After 6 months, infants that are entirely breast-fed or formula fed are at risk of developing iron deficiency, so solid foods are important. In particular foods rich in iron such as pureed cooked meat, poultry, boneless fish, cooked eggs, tofu, lentils and legumes are important to introduce.
An excellent and comprehensive on-line resource on this matter can be found at:
http://raisingchildren.net.au/articles/when_to_introduce_solids.html
If you are having troubles introducing solids or unsure of the particular needs of your infant it is important to see your GP for a full assessment of the baby and professional advice. At Busselton Medical Practice we have experienced doctors who are knowledgeable in this area and would be pleased to help.