I want to quit my job before having one lined up. Will I find one quickly?

Hi, I was born on 10/9/72. I work for a difficult person who has made my life miserable and has created a lot of stress. I want to give my 2 week notice now and hope a few places I've applied may come up in the next few weeks. This situation is making me sick and I believe there is always a way to make life happen. Also, there is a strong chance an old job may be offering me a position in the next two weeks. Should I give my notice now before the other places make an offer? I want to but I'm a little nervous.