The very front rotor closest to the radiator is rotor 1 as in L1 and T1 right.... IF not mine are crossed. And my trailing.

 

like boingers, the cylinder (or in this case rotor housing) nearest the crankshaft pulley is No. 1. The leading plugs are the lower of the two holes on each housing. I would suggest replacing each plug one-at -a-time so as to ensure the correct plug lead is reconnected.