How long till real labor?

Had my 38 week appointment today and my blood pressure was a little high so they sent me to triage to be monitored. All ended well with that but while I was being monitored the nurse noticed my contractions were regular and 4 minutes apart. They decided to check me for dilation and it turns out to be only 2cm.. After they checked I ended up having my bloody show at the hospital on the bed. It was so embarrassing, but the nurse said it was normal after being checked.  My contractions continued and they said I am in early labor and they don't expect me to make it till my due date. How long does it take after the bloody show for full labor to start?