Starting audio before video

So I just starting using Final Cut X and editing in general and am stuck on some audio editing. I've tried looking around the internet but can't seem to find what I am looking for, probably because I don't know the technical name for it.

I am trying to start the audio from one clip before the video starts in the middle of a scene. A friend recommended I separate the audio and video and hold the option key and drag the audio file but that starts the audio way early in the scene that I want. I really hope this all makes sense

Any help would be really appreciated!

support.apple.com/kb/PH12635?viewlocale=en_US

FCP X has a great manual. You can find it under the Help Menu.

That's called a J cut.
Select the clip that has the audio you want to extend. Press Ctrl+S and then drag the audio out to where you want it to start (or the video in if you already have the audio where you want it, but too much video).

The link that Soundwise gave you also has the information and more.

To expand a little on the other posters: most of us, when starting in FCPX, have a temptation to separate the audio because it feels more comfortable like this, like we have more control. In practice, you almost never need to separate the audio tracks - expanding them (double-click the waveform in the storyline, or ctrl+S) usually gives the control you need.

All of this is covered in the manual, and if you're new to FCPX it's worth spinning through it. It's a very different way of thinking about the editing process to anything you may have used before, and while it's quite self-consistent it's not necessarily obvious or intuitive for that initial learning curve.

Ah! It's so simple!!!!!!! Thanks everyone!