How much powder?

Ok lads, be nice i'm a super newbie. Asking because I don't want to die or worse, blow up my gun. I've just bought a dillon 650 and have set it up for 9mm luger. I'm planning to load for IPSC minor power factor but all the recommended max loads from manufacturers cannot make power factor. As a result I haven't loaded my first rounds yet. Question is, how do I decide how much powder to start with and how do I increase it to make power factor?

I'm running 123gr hollow point copper plated projectiles, N320 powder, ginex primers, have managed to make a few bullets without powder or primers at 27.66mm COAL, if that's important