With my first I started losing it around 37ish weeks but losing your mucus plug doesn't mean you'll go into labor soon. I ended up being induced at 39w1d with that pregnancy. Losing your mucus plug means nothing on timing of labor it could happen 2 hours after or 2 weeks after lol
with my first, it started a little here and there around 20 weeks, but I didn't have my bloody show until I was already in active labor and 3 cm dilated
I'm 18 weeks and have already started losing little pieces. it regenerates all through pregnancy. A lot of women don't even lose the whole thing until they're already in labor, others lose and several times and it grows back.