"In all infants, in consideration
of their nutritional needs, developmental abilities, and reported associations between the timing of introduction of complementary feeding and later health, which are
discussed later, the introduction of complementary foods should not be before 17 weeks but should not be delayed
beyond 26 weeks."
It makes a point of introducing foods which are age appropriate and safe for the baby, according to developmental ability. It is clearly different for each child, and it also says that because the necessary hormone responses are actually governed by the introduction of solid food, it is not the baby's gut that 'matures' at six months, but the introduction of food that makes the gut and bodily systems respond in kind.
It also talks about the importance of protein, fat, carbs and vitamins and minerals such as iron - its not as easy a introducing a bit of carrot or sweet potato at 6 months - it sounds like they need more than that. 90% of a breastfed baby's iron needs to come from food, and eating beef aged 5-7 months is associated with a better haemoglobin level.
It also says to introduce gluten (alongside bfing if you can to help prevent allergic reaction) pretty early - not before 4 months but not after 7 months - this has been associated with preventing coeliac disease.
Very interesting. Clearly not one size fits all, but I personally would wait until LO is able to sit up (with minimal support) and able to ingest something himself - picking it up, putting it in his mouth and eating it, and after that I would get going pretty quickly on most foods. If this happens at 5 months, by the sounds of it, it is fine.