I agree there is a window between the magical 4-6 months age to start solids. DD was just one VERY adventurous and interested in food baby and started at 16 weeks. She didn't push any food out at all and wanted 3 meals very quickly (she was BF on top of the foods too).
DS however, wasn't as interested in food yet started at 5 months and slowly built up to the 3 meals. Both were eating what we ate by 9 months (obviously the suitable bits).
I do think more research needs to be done on the types of breads we have on offer though. The huge numbers of people who are coeliacs or intolerant to gluten now is incredible. More research NEEDS to be done.