Sometimes AF does not announce their promotions/special fare until a month or two before departure. It depends on period and loads. There are many Z fares. Sometimes the cheapest Z fares are unchangeable or changeable for a hefty fee, so booking early can be risky. It used to be that buying early (in your case 6+ months ahead) would provide the lowest fare. But I am not sure that this is now the case in biz. You can get the run-of-the mill fare, but Spring seasonal promotions will not be offered (if any) until winter, probably late winter. Airlines have to be flexible as demand is so volatile.