Belly’s dropped

So I’m 31 weeks and my baby girl has plummeted down! She used to sit so incredibly high up in my ribs that I was able to wear my pre pregnancy jeans and still button them! But this last week she’s as low as she can go and hanging there. The heartburn has stopped and I can finally breathe, but She’s pushing hard against my cervix as well. Braxton Hicks contractions have started getting pretty strong, like catch my breath strong. This is my third baby and I remember with my first she dropped maybe a couple weeks before labor came on. My second was a bad pregnancy and she was low right from the start and she spent the second trimester on trying to eat out early. This has been a very long and complicated pregnancy as well and docs have been watching for preterm labor since 22 weeks when I was hospitalized with contractions. There was placenta previa that had us set for scheduled csection but by miracle it resolved and we are now open to natural labor and delivery, as long as everything goes smoothly.

My question, ladies, is how long after this happened to you did you go into labor?