Keep in mind that while they can be hard to distinguish from the real thing, they're not efficient enough to push your baby out just yet the way actual labor contractions are. (whattoexpect.com)
I think I was in very slow labor for about a week and then in actual labor for 36 hours. (breastfeedingtoday-llli.org)
Many women experience these for hours, or even days, before actual labor begins, with contractions coming at irregular intervals. (fitpregnancy.com)