Well, it depends. If Uxie LV.X is popular now, I wouldn't wait. I'd get rid of it now! The metagame determines if you should sell now or not. I would sell a Luxray GL LV.X before Nats or something, because it's a huge tournament and players are dying for cards that they don't have. You can make top dollar from the people who don't get their cards ahead of time.