Apropos 'mag' switches on or off & starters.
I understand a pre WWI Rolls Royce car engine was started from stationary with a shower of sparks. With the Potez flat four, there were a few notable occasions where she too started from stationary.
After manually propping to suck in & back in the cockpit I switched the ignition tumbler switches on. [i.e. no starter which I rarely used]. This alone could yield a propitious spark into the fuel air mix in a cylinder & away she went.
Moral: A prop is ALWAYS live.
mike hallam.