I can't give you a good answer honestly...I'm so close with both my parents. I remember I told my mom I thought I was late with my period, she said "okay" and the next morning woke me up with a pregnancy test in her hand. We literally took it together.
My dad on the other hand....Were close but he's more strict, we waited a couple months and then told him. He was dissapointed, which I mean duh...They're gonna be dissapointed, thats just something you have to expect.
If I was in a situation where i'd have to tell my parents, but not being as close to them as I am. I think I would write a letter. A letter is always good for serious things because you dont have to say it to their face, you dont have to worry about crying & chickening out. Just write the letter and give it to them.
Personally, I wouldnt bring my boyfriend when you first tell them because sh*t could hit the fan lol...
If you need anymore advice just message me.