I reckon it's best to wait till baby is ready and able to eat. Allergies are just one piece of the puzzle (and there are lots of other variables involved there)
Heinz et al will be clapping with glee With the recommendation dropped to 4 months, a significant proprotion of parents will start from 2-3 months. I think that's probably the best reason to leave the official guidelines unchanged. Many parents don't wait till 6 months now anyway, with a significant number starting at 4-5 months, so they're already hitting the 'allergy sweetspot', apparently.
Anyway, maybe it's time to go out and buy shares in the baby food companies