With no tail wind or crosswind less than 20kts it's a two step procedure, 50%N1 is the first step and for second step all it says set takeoff thrust. The procedure for tailwind or crosswind more than 20kt is different. It has three steps. First is same 50% N1, second step asks you to rapidly move thrust levers to 70% and third step ask for moving thrust levers progressively to takeoff thrust. So how the thrust levers are to be moved in the two scenarios is quite clear.