My DS had a single peanut when he was slightly over 2 yrs old, and he developed nut allergy. Lots of people here often think that we, mums of very allergic children, are over reacting, but considering that we have no allergies in the family, and DH and I came from countries where nut allergies are unheard of, I suppose that if I had the chance to turn back time and ask the same question again I would ignore the midwife, hvs and GPs who not knowing anything about allergies swear that peanut butter is OK, I would ignore all the mothers who have used it (including mine) whose children had never a problem with it, and follow the guidelines, I would wait until DS was 3 or probably five, as someone said in another thread, a moment of pleasure doesn't justify a lifelong of misery. Giving nuts to under 3s is like playing russian roulette, you are likely to be fine but you may, as some of us had, get the shot .
Appologies if I seem OTT, I have just got very bad news about DS allergies and I a bit sensitive about the subject. sorry