Everyone's different and I think if you know your child and our pediatrician gives you the okay, why not try it? I was told and have read that if the baby is exclusively on breast milk, it's better to wait until 6 months, but if they use formula, they can start as early as 4 months if they're ready. At my 4-month appointment, my pedi said it was fine to start on rice or oatmeal cereal (I breast feed but also supplement with formula and my little guy is hungry ALL the time!!!). I haven't introduced it yet because the in-laws are visiting and his routine has been all over the place and I want to use it around the same time every day. Anyway, nobody here is an expert and every child is different, so why not let people make up their own minds? If you start at 4 months, great, if you're waiting until 6, great.
Re: stage 1 foods