Hair dye in 1st trimester??

Ok ladies, I need opinions! I've had this appt scheduled since before I got pregnant. I'll be 5 weeks 3 days. I get highlights, so no dye right on my head, and at a salon, so it's well vented. I've been researching and most websites say there's really no research that it's bad, but some suggest to wait until the 2nd trimester. What do you all think??