Second and third time mommys, how long after your baby dropped did you go into labor?

I'm 36wks 3 days with my 3rd, 30%effaced & 1.5cm. I lost my mucus plug on Sunday (the 23rd) had some slight nausea that comes and goes and a little diarrhea over the weekend. Yesterday I noticed my tummy was a lot lower.....my mom even commented that I am visibly carrying lower now. I have read that subsequent pregnancys tend to drop right before going into labor.....how long did it take for you?? I want to know how true that is? Thank you!!