Linea Negra

For those of you that HAVE gotten a linea negra , when have you gotten it ? With my first pregnancy I I got it all the way up to the top of my stomach and it was pretty dark , I'm almost 6 weeks pregnant and when I was going to take a shower I noticed a dark like starting to go up . I thought it was just my yoga pants leaving an imprint but they weren't even tight at all & I took them off 2 hours ago and I still have the line LOL . I didn't get it until I was in my second trimester with my 1st pregnancy so I'm so confused!