Dropped baby

Okay so I'm pretty sure that my baby has dropped when I get BH his butt is now right on my belly button and usually it's higher. and now I'm seriously having so much pressure when I'm sitting down I was also getting that lightening crotch pain but not too bad. I felt a punch or something in my pelvic area last night and I've been having fake contractions.

So my question is when your baby dropped how long did you go into labor after? I'm only 35 weeks tomorrow but I just feel like he's gonna come early.