Anyone thinking labor soon? HELP!

So I had my first weekly OB today. I'm 36 weeks 1 day. Doctor said I'm 3 cm dilated, 80% effaced, and his head is "crazy low". My first son was born at 36 weeks 4 days and my second born at 38 weeks 2 days. I didnt think to ask her what she meant by "crazy low", but she mentioned she could feel his head. How soon does anyone think I will go into labor? Anyone experience similar measurements and it happened fairly quickly? Not really contractions, but I have had sharp cramps down there and "lightning crotch". I never really had contractions until I was actually in active labor with my other boys. Lol Feel free to share your experience! Due date is March 6th. Baby boy number 3 :) thanks for your input in advance!