Assuming I'm not booted tonight or on Thursday night, I want to make sure they don't decide to vote me out while I'm gone. (that would be an awful way to go out.)
My preferred outcome would be to win immunity on Thursday and not have to worry about it. But assuming I don't win immunity, my plan would be to post my idol in the public forum and say "Hey everyone, I'm not going to be here for Sunday's vote, and since I would hate to get voted out without even being here, I'm going to be playing my idol to keep myself safe." I would post the idol too, and since everyone would see it, I would really hope they wouldn't vote me out.
But I honestly wouldn't play the idol. Just the threat of me playing it would hopefully deter people from voting for me. After Sunday's vote, there will be 6 people left, which means I would only have two more tribals to play the damn thing. So I would definitely play it at the next tribal to make my bluff not seem weak. Or I could hope to win immunity at one of the challenges and not have to worry.
Basically, I think that my idol can keep me safe for 2 votes, and if I can win an immunity challenge Thursday night or after, that's 3 votes that I'm safe for. If I can get to the final 4 or 5, I think I can really win this thing.