How do you sync Audio in FCPX (Manually)

I was wondering how you are syncing the audio in FCPX for the correct timing?
Syncing the video frame with the visual audio peak or syncing the video frame with the audio frame where you hear the audio?

I have noticed when syncing the audio peak right on the video frame and moving frame by frame you will hear the audio frame earlier in example a clap or door shut.

I find that odd...

Looking at the current frame in your timeline there (the shaded area in the timecode strip), it looks to me like the audio peak hits just before end of that frame. In which case I'd absolutely expect FCPX to play that sample on the frame as you indicate.

Remember, audio in FCPX doesn't have to move by frames. You could back it off a few hundred samples to shift it into the next (video) frame, if you chose.