FWIW my DD started BLS at 6 mths but wasn't really interested until past 7 mths. One day she suddenly started eating everything and never looked back. I think that's the advantage of BLS, baby will eat what they want when they're ready and not before. Some research into babies digestive systems suggests babies are ready to take in other food apart from breastmilk between six and nine months. I do know of one 10 mth old that wasn't really interested in solids and he was thriving! If you let him set the pace, there's really nothing to worry about.