Work and pregnancy

I work as a PCT (Patient Care Texhnician) very similar to a CNA. And I just found out I'm pregnant. I'm also 5 weeks now and I'm worried about my safety and the safety of my pregnancy. My ob won't see me until I'm 8 weeks, so other than a positive pregnancy test I have no documentation as of yet. How soon would you tell your employment? I know there is a wait period for most people, like once in the second trimester, but I really don't want to do anything to compromise this pregnancy.