Mild cramps at 38 weeks

I've been having mild cramps ever since Friday. Sometimes it's consistent but other times it goes away. I keep hoping it'll get worse. I've been walking for a long as my body allows me to and I get cramps sometime after. I also squat and workout on the ball. This is my third kid and I went into labor on my own with my first two but I'm anxious. How long will it be before I go into real labor?