Probably not a great deal of help, but I remember Fred Williams in Wolverhampton definitely stocking one of those circa 1990 so very late 80s into 1991 seems a safe bet.
Even at that age, when I didn't know all that much about road bikes, the idea of a pink Bianchi* just seemed a bit wrong!
David
*Nowt wrong with pink bikes as such, I always liked the pink/black Peugeot machines of the same era.