For what it’s worth, I never bought any manuals or any other how-to materials. Final Cut shipped with a tutorial DVD. I viewed that and picked up the (very) basics. Then I just plowed in and started editing.
Hit a roadblock, Googled it, read how-to articles, listened to podcasts, watched tutorial videos, even occasionally RTFM (online, of course.) Rinse and repeat.
You’ve already found the Cow, so you’re already light years ahead of where I started. 😉
Just do it.