Bows can do funny things. I've had the nocking point so low that the cock vane was getting deformed from hitting the rest and all while shooting bullet holes through paper. Next for brain burning, I've seen rests off badly and when shooting through paper a bullet hole came at longer distance, but then the arrow does correct itself. Even of the best tuned bows the arrow can be on it's worst behavior around 10 to 12 yards. Okay, it happens for no reason.
Bow timed and all, I want the arrow coming out of the bow a little tail high. This way I know the arrow is basically coming out of the bow cleanly, no rest contact. I then set center shot back to the power stroke of the string.
Eye ball/align the string to the groove of the upper cam or wheel and see where the arrow is. If off, move rest so arrow aligns with the string aligned to the groove of the cam or wheel. Just like any center shot procedure this is a starting point.
Weird things still can take place. Aggravated to no end I have set center shot using a chronograph. Here, you look for the highest fps. Once found I go a bit farther with the rest to see if fps drops - you have so much of a span (little) where the highest fps will be recorded, so find the happy medium.