Not sure about the quick succession thing but I have definitely heard of introducing foods early alongside BFing. I heard of it in a trial being conducted here (in London) at a major teaching hospital. Basically researching the benefits of introducing allergens (wheat, dairy etc) alongside EBFing. Perhaps they've finished the trial, come up with the results and are now recommending it? FWIW, as far as I remember, it wasn't really 'starting solids', more just giving them small amounts of allergens to get them into their systems.