When did you get stretch marks?

I'm almost 22 weeks with twins and I have not gotten any new stretch marks, and stretch marks run in my family. I did get stretch marks on my sides when I went through puberty. I've been drinking a lot of water and using coconut oil on my belly and back 2-3 times a day or whenever I feel dry. I was just wondering when you noticed your first stretch mark in any of your pregnancies if you got any at all?