So on tuesday my school is going to have some back to school event and my dad wants to go with me. Which led me to the conclusion that it'll be good day to come out because I've been wanting to come out and it seems like on tuesday I might have the opportunity to do it. Any advice?
Just be yourself. Unless you have a particular reason to think he will react badly, it will most likely be a positive outcome for you. Just remember, if you do, it's also possible that he may not initially react as well as you want, but may need a little time to adjust in his mind. Be patient with him too. Good luck!
I think it's best to come out when you can sit down and talk with him (like over lunch or something) so if that's the kind of environment this back to school thing is going to create (as opposed to standing around in a crowded rooms mingling with people) then I say go for it!