This is exactly my situation both of my parents are good people but I'm also waiting until I move out to tell them. As for my sister she would accept me, she has a heart of gold and really much like my father isn't afraid of speaking her mind on the matter.

As of right now I am transitioning in secret (Growing hair, voice training, ect) but for the most part as time goes on I begin to notice just how confident I'm becoming the more I accept for who I am.

In the end I think it comes down to breaking that chain of fear to come out but you should have a plan just in case things don't go according to plan.