Sometimes it can take a few days for you to notice a reaction, depending on the severity and type of reaction. When I first started giving solids I did 3 days at a minimum. At this point, knowing he has food allergies and knowing that his reactions are not always immediate, I am going at least a week. In your case I would advise a 3-day minimum for most foods, but up to week for the more allergenic foods (dairy, eggs, soy, wheat, corn). Considering the family history of food allergies, I would also wait to introduce these foods until your child is at least a year. I would wait 2-3 years for peanut butter and tree nuts.
HTH and good luck!
Jenn - still breastfeeding
ds 12/04 - milk, eggs, beef, wheat, peas, avocado, zucchini, sweet potato, winter squash, spinach, tree nuts, sesame seeds. Also avoiding peanuts, sunflower seeds.