Bicnod I'm an anaesthetist so I have no qualifications in this area. However, I've copied this from the WHO website:
"Around the age of six months, an infant's need for energy and nutrients starts to exceed what is provided by breast milk and complementary foods are necessary to meet those needs. At about six months of age, an infant is also developmentally ready for other foods."
To me the key words are "around" and "about". All babies are different and if you think J is developmentally ready (ie sitting up unaided and lost the tongue pushing stuff out of mouth action) then to me he's likely to be one of the ones who's ready a bit earlier. My DD, on the other hand, is 12lb and barely sitting up even though she's 5 months tomorrow. There's no way she's ready.
However I am happy to be flamed by more knowledgeable people. I just think all these guidelines need to be used alongside a wee bit of common sense.
Disclaimer: when I weaned DS his sleep went tits-up for at least a week. And J's sleeping (or lack of it) and clinginess may have nothing to do with hunger. Only you can make that judgement.
Sending you lots of
and
.