Actually you can not set any % N1 with reference only to the Thrust Levers. The FCTM refers to the TLA, Thrust Lever Angle symbol or "doughnut", not the Thrust Levers.
If doing a static take off then set 50 %, wait for engines to accelerate and stabilize, release brakes and set FLX / TOGA.
The FCTM states:
"If cross wind is at or below 20 kt and there is no tail wind
• From idle to 1.05 EPR / 50 % N1 by reference to the TLA indicator on the EPR / N1 gauge.
• When the engine parameters have stabilized, to the FLX/MCT or TOGA detent as appropriate."
Then:
"This procedure ensures that all engines will accelerate similarly. If not properly applied, this may lead to asymmetrical thrust increase, and, consequently, to severe directional control problem."
CP