I don't think it's bad. There are some people who think it'll harm the baby but I don't think there's anyway that can happen by dying your hair
Wait until your second trimester 12+weeks, i'm not sure on the reasons but it's not good for the baby before then
Its perfectly fine as long as you're in a well ventilated either.
I've read that dying your hair is fine once you've reached the second trimester, since everything is really delicate in the first trimester and you have to be extra careful. :)
My cousin is a beautician. She was dyeing hair throughout her pregnancy everyday. Her son is 18 months old and perfect. My doctor says its safe to dye your hair. If it wasn't, people that do hair for a living that are pregnant, would have to quit their jobs. It's safe. You're fine. I personally chose not to dye my hair in the first trimester, but it is safe to do so.
I heard u should wait until ur out of ur first trimester cause the chemicals or whatever. Most birth defects are formed in the beginning and its just a crucial time for ur developing baby anyway(: