Dying your hair while pregnant with twins

I am 13 weeks and 3 days pregnant with twins. I asked my doctor if I can dye my hair or bleach it because I usually go to a very light blonde but my natural hair is dark brown. As per my doctor it is safe to dye my hair because there is only very little chemical that goes through your scalp. So today I have decided to go back to blonde because I grew more than half of my hair our already to only my ends are blonde.

What are your thoughts? At how many weeks did you dye your hair?