When to announce pregnancy?

I'm 23 and back in march I got out of a 6 year relationship that I've had 2 kids with the person. Come to find out I'm already pregnant with my new boyfriend and we've been dating for only 3 months. My mom has been living with me for 4 years and I dont know how or when to tell my mom. I know I'm an adult and I can make my own decisions I'm just scared of what she'll say. I'm scared of her being disappointed in me for getting pregnant so soon.

How should i tell her?😞