Does implantation bleeding always occur when pregnant?

Ha

I’m about 7 DPO (I’m getting all the major pregnancy symptoms) I know it’s still early to tell but I’m curious if implantation bleeding always occurs during the first few weeks. We didn’t use any BC on my ovulation date (and he didn’t pull out). I’ve had a couple times I thought I was pregnant but always turned out to be negative so I’m not trying to get my hopes up