I think 11 months out is never a good time to buy a ticket - unless money is truly no object. BA often don't load the lower fare buckets for some days/weeks after the flight goes on sale, and in the next few months there's high probability of a sale. Unless it's a very high demand route (e.g. major sporting event, cherry blossom time etc) it's unlikely to sell out for some months so I'd definitely sit tight and keep an eye on prices.