30wks2days pregnant1cm dilated cervix fully effaced no measurable length strict hospital br last 4wks given mag for 12hrs 4 days ago baby coming soon?

Can't say for sure: Certainly what you describe is a worrisome picture given you are dilated, have no measurable cervical length, and you are only 30 weeks. The magnesium you were given was likely for neuro protection -- indicating your OB has been equally concerned about you delivering early. That said, no one knows how soon you will in fact deliver. I am certain every attempt will be made to prolong the pregnancy.

Ask your doctor: I'm sorry your doctor has not answered this question for you. The truth is I do not have enough information to give you a prediction. Based on the above you will probably deliver before 36 weeks, but impossible to say when.