I agree with the suggestions of going by the individual baby rather than a set age. I waited for sitting with support, loss of tongue thrust reflex and interest in food. For us that ended up being at about 5 months. He was also 98th centile though. I have always found it a little strange that babies all crawl, walk, say their first word etc.. at completely different ages but are all expected to be ready for solids at exactly the same time? Think it also depends what your reasons are for starting, if it is because they seem ready and interested then fine, if it is because you (not you in particular but anyone) think it will help them sleep through the night then probably not! Incidentally, solids didn't make one bit of difference to our guys nocturnal activity!! Go with your mommy instinct.