What car?
Knowledge from others car, TDC at first cylinder, the rotor should be facing the "spark-end" for first cylinder's spark wires. Usually PAST it. (I am not sure if this make sense)
You shouldn't have to worry about the position. It should have a groove, and you should only able to put in at FIX position.
I am not sure if you understand, I can't explain it really well. But hope this help