Should I wait before comming out as bi to my dad? (long)?

Well, I think the decision is definitely up to you. However, your ual attraction is none of your parents business. However, if you find yourself dating a girl, that would be a good time to let them know, and instead of being all awkward and being all "um, yes, I am coming out" you can just be like "hey, this is my girlfriend, betty" or whatever. Its also an actual inscentive to come out.