I was flicking through a book in the bookshop the other day called Top 100 baby purees by Annabel Karmel. It was really informative and had great recipies and mixtures for the various different ages and had a section on what foods to avoid (and why to avoid them - not just a list - which I really liked about it)

Maybe you could see if your local library has it or grab a copy from the bookshop - I think it was less than $20.

Actually I think that I have just convinced myself that I should go back and buy it

Sorry that I can't remember the specifics at the moment but I think that there may have been something in there about avoiding citrus and tomatoes until later - not for allergy reasons but for the acidic taste - wish I could remember.