Week 37+4 - mucus plug, bloody show, early labor

Yesterday I thought I was losing my mucus plug in bits and pieces and today just confirms that I was. Started the morning with a small speck of blood, then later during the day saw a string of slightly blood tinged mucus, and since then I've had spotting. As of this evening I've felt more uncomfortable tightness in my lower abdomen making it especially uncomfortable to walk. Some of the tightness is painful like a period cramp and is coming in waves, making it  seem like these indeed are the early labor contractions that I've been reading about. 

I'd love for these babies to hold on until Tuesday morning when the better OB is on call. Or maybe at least until Monday when the MFM is in the office. I really wonder how all this is going to go down. Based on my ignorant gut feeling I'm going to venture a guess that there is a 50% chance we'll be going in tomorrow.