California USA (born and raised in Australia))
I have followed the most common advice and given my first rice cereal.
With my second it caused constipation so I used oatmeal, and used oatmeal for my third.
Since that time I have become more aware of what is on food labels and have begun to question everything we put into our mouths. My main desire from the very beginning has to give my children the most nutrients and healthy start as possible.
Until baby 3 I was quite unaware of the labeling of foods and have opted to skip anything from a box for my 4th.
I feel I did what I knew was best 4 years ago but now realise I am enightened and would not feed that to my baby. While I have not noticed any adverse reaction from any of my children I am obviously unable to comment on any long term affects, if any.
We have always had our baby in a routine from the beginning; encouraging them to sleep during the night and take as much milk during the day. All 4 of my children have slept through the night by 14 weeks or less, and I have begun them on fruit/veggies before 6 months.
There is debate about when to start first foods, and I begin when my child seems frequently less satisfied, needing more feeds during the day, and even waking up again at night. If my child wakes up during naptime due to hunger and during the night then he/she is not getting the rest they need and this is a sure sign to begin solids, whatever that may be.
This time around, for my 4th, I plan to give fruit/veggies mixed with a soft and runny egg yolk (no whites) for protein. However, I will just begin with fruit and veggies first and then mix in the runny egg yolk when we are established on solids.