Best Trap to vent Distance for Shower vent

I am installing a new basement shower. I have the vent at about 12" from the end of the trap.. I assumed that keeping the vent as close to the trap as possible would always be best and help to keep the trap wet. Am I correct or should I set it back further? or does it even matter as long as within code?

Thanks in advance..

2" trap = 6' to vent max.

vent

Within code is all that matters.