Soft cervix at 33 weeks?

This is my second pregnancy and with my first he had to come early (38 weeks) because Dr noticed he stopped growing. I had to be induced with him and cervix got softened by meds. Well, this time I'm having some pubic pains and Dr says my cervix is soft and the baby is very low. I already know that I may have to have baby early because of growth conditions from first baby but I'm wondering about how long after cervix get soft does labor start? I'm 33 weeks pregnant and a little nervous she'll be coming before we planned.