I'd disagree with some of those statements, some people have an inherent need to feel accepted and to feel like they belong, and for some people such a feeling is inaccessible if they're not open about something that they consider important to them, like their sexuality. In which case, even if it's not being discussed, their sexuality could be a big deal to them. I also disagree with the lying part, some parents are not accepting at all of sexuality and may confront you about it, and if you told the truth in that scenario the circumstances could be less than fun.
But BillyBobJoe does give a good point, one of the main things you should do is try and be confident, but at the same time sincere and formal. If you fear the person will have a bad reaction, it's more important to try a more formal approach in which yes, you go "SO, I'm bi, if you have any questions ask them", if you feel your friend won't mind then say it with confidence and ease, like "Oh, btw, I'm bi
". If you act like it's not a big deal, neither will they, provided they haven't already decided being gay is wrong or something.
You also got to remember you don't have a time restraint, so come out whenever you want to. I'm glad you sent a picture though, keep us updated on how it's going!