Could be soon, could be weeks. :( I had a lot of pelvic pain, some lower back pain, mildly increasing discharge, and increased, softer BMs all this last week. (The worst of the pelvic pain lasted about 12 hours - still hits in smaller, milder doses. Just as a warning.) DS feels like he's lower, people are no longer assuming it's twins, and the pelvic pain isn't impeding movement much anymore. DS has also gotten all hyper - hope he turns, but doesn't flip (head down, but sunny-side-up). 39+2 here.
Diarrhea is a better sign that labor is imminent than just more BMs. It's one of my "call the midwife now" indicators.