I wish I had enough of a theological background to give you more input, but as Ugly said, the Bible states the time will not be known! It does say that the world will be more wicked than ever (please tell me it won't get much worse!) And that when it happens those who are left behind will be led to believe a lie about those that disappear!
I suggest you should find the verses in the Bible, read them, think about them ("meditate" on them), and maybe even ask your parents or a youth leader about it! I know my youth leaders LOVE when we ask questions. Haha.