Stretchmark

When did your stretch mark starts to appear ? And how little/bad is it ? Ive been applying bio oil and palmer’s since 1st trim in hoping i wont get. And it was all clear until now, 34++ weeks suddenly i see some dark stretchmark on my left lower belly 🥲🥲🥲 i believe what caused it was also from the itchy hands scratching tummy. Cause i dont believe scratching tummy eill cause stretch mark. And now its there. Will it gets worst as pregnancy progress? Heard that it’s genetic but will it fade after birth if i continue using the oil and cream ? #FTM