How do I tell my older sister I’m pregnant?

I just turned 21 a week ago and and I turn 12 weeks tomorrow, I live my with my older sister and her 10 yr old and 1 yr son, I’m not working right now but I am in school for a medical assistant I graduate for 4 days due before my due which 09/17/19 I knew about my pregnancy since Jan but I don’t know how to tell her what is a good way to tell her?

Update - I told her and she took it way better than I expected she’s supportive as long as I finish school ❤️