When to tell work?

I'm 6 weeks 3 days and I am running out of PTO very quickly due to some sickness I had in the beginning of the year. My boss is going to work with me so I can make up 60 hours. Since I'm still so early when do I tell them I'm pregnant? I'm the type of person that gets things done right away. But I've had a miscarriage before so I'm nervous to tell them then something happens. Oh btw my father works for the same company and we are not telling our family's until the 12 week mark.