Ah, man, the friend zone. Yeah, I remember those days. You eventually learn that you have about a 48 hour window of initialization where you have to make a move, otherwise it's a tough, tough climb. I made it out of the friend zone once, man. Had it not been for several thousand miles and a continental landmass, I'd probably still be with her.
If you like her, man, tell her as soon as you can. It's worth it. But, importantly, don't get super attached to her. Tell her once, when she's sober, and she'll always know. Act on it once, as well. Don't be awkward, and if it happens, help it happen. If it doesn't, then you need to move on. Life isn't like a Rom-Com, friend, and the nice guy doesn't get the cute girl he's loved all his life. That kind of singular minded devotion to a girl who you aren't dating is actually destructive and prohibitive of making things happen.
So, if you end up liking her immediately, move. Be everything you know you can and would be up front, and you'll have a much better chance.