39 weeks pregnant dilated to 4cm for a week now but no contraction?

Nobody can predict that. It could happen today or you could go overdue by a week or more. If you are feeling crampy and tightening at regular intervals or start seeing a lot of bloody show, or if your water breaks, or if you start feeling severe rectal pressure (much more pronounced than what you're probably feeling now) head to the hospital right away.

I was 4cm and 80% effaced and walked around for 4 days (no pain) before I finally got so anxious I just went in. I was only at about 4.5 to 5cm at that point but they decided to start me on pitocin since once you reach 4cm you've already passed the first and hardest part of labor. Once they started pitocin and broke my water, I had my daughter within 6 hours.

WITH MY FIRST CHILD I WAS 1 CM DIALATED AT 21 WEEKS SO THAT HAS NOTHING TO DO WITH HOW SOON YOU MAY GO INTO LABOR,YOU WILL KNOW IT ONCE THE CONTRCTIONS START THEY FEEL LIKE PERIOD CRAMPS ONLY 100 TIMES WORSE IN MY OPINION.WITH MY DAUGHTER THO I WAS DIALATING AND LIKE YOU FELT NOTHING UNTIL I WAS 8CM DIALATED BUT WITH MY SON I FELT THEM RIGHT AWAY! GOOD LUCK AND HAPPY NEW YEAR!

Wait until you go into labor as millions of women have already done.