Sorry about the late post. My first suggestion is probably unhelpful, but it is: it’s up to you. You are the one who knows your friends. How and when (or really even IF) you tell them is totally up to you. It’s most important, though, that you are completely comfortable with yourself first. Your posting makes it sound like you are, which is a very good thing. Some people write it down or send a text. Personally, I prefer face-to-face so that there is no confusion and no one thinks I’m just joking. If you two close friends are very close themselves, you might either want to tell them together, or if that seems too stressful – especially if you have serious concerns that either one of them may react badly in any way – individually, but then I would follow-up telling the other one as soon as possible, before they have a chance to communicate with each other.
Personally, I found it easiest and best to come out just to my straight best friend first because I knew him well enough that I was very certain about how he would react to the news (although you can never actually be certain about how any individual will react until you confront them with it; people can surprise you – fortunately, in my experience, most of the time, the surprise was in how openly accepting they were when I was expecting at least some hesitation, if not fearing outright rejection.) Not that it was easy (after all, you feel exposed and extremely vulnerable whenever you confide something so personal and private to another individual) – I must have danced around the subject for over 10 minutes, while he kept listening but started to get a bit impatient, before I could finally blurt it out. He just laughed a little (gently, not meanly), told me he wasn’t really surprised, was honored that I had chosen to confide that in him and told me that it didn’t change anything in our friendship.
I hope this post isn’t too late to help.