It's apparent that everyone's circumstances are unique to them, and what works for one person might not be right for someone else. Employment situations, family closeness, culture, one's own sense of self and personality, and everything else are all brought to bear on deciding how and with whom to share that information. And besides, telling someone that you're growing breasts is pretty much the same as, you know...
How NOT to ease your friends into realizing you are growing breasts:
You: Hey Mike! What's happening?
Mike: Dude! How ya doing?
You: Just Great! Hey, I wanted to tell you something...
Mike: Hey, you aren't looking so much like a dude, lately!
You: I know!
Mike: What's going on?
You: I'm growing breasts!
Mike: What the #&@!?
You: Yeah, man, I'm growing breasts! I wasn't going to just come right out and tell everyone, but they're getting so big and jiggly! See?
You: <both hands jiggling breasts>
Mike: Yeah, I see what you mean...
You: Here, you wanna squeeze 'em?
Mike: F#$@ man! No, No I don't!
You: It's alright, man!
Mike: F#$@! Stay away! I don't wanna touch those things!
You: Come on, man! You'll love it!
Mike: Yeah, yea, but... a... You mean you're...
You: Yeah, man!
Mike: Wow!
<Long silence>
You: And stop calling me 'Man'!