First off I would repeat pretty much everyone who has responded so far by saying, don't lie to your therapist about how or when you began to realize you were trans. Every transsexual person I have ever met has a completely unique story. Yes some of us had similar fantasies as children, some of us realized at about the same ages, but none of us are exactly the same. It is normal to have realized/accepted this about yourself at any age regardless of how you acted or felt growing up. We aren't taught as children to question our gender, we are taught that we are this or that and that's the end of it, deal with it, live with it, accept it no questions asked. Often as kids we just follow along with these types of rules so don't let your past become a fear or a doubt in yourself. If you don't doubt it neither will anyone else, it is our own strength and determination that others see in us.
As far as the genderqueer thing, I'd feel a new therapist out on this issue. Perhaps just bring it up as light conversation, even if you don't do so in your first session. Ask if they've heard the term and what they know or think of the whole idea of genderqueer. Just act curious if you are to scared to straight up say something one way or the other about how you personally identify. Discuss the entire issue at some point, either right away when you know their view or sit on it a bit and plan out how you'd like to tackle the subject once you know more about their views and education on the matter. If they don't know much about it then help suggest materials they can study or look at to get a better idea of the concept.
Also draw some comparisons between genderqueer and other kinds of "accepted life choices" (obviously I'm not saying genderqueer is a life choice but my following examples are). Like guys who are into certain kinds of music scenes, they wear make-up and even some female clothing. Don't let them make you feel like it isn't normal to be a guy and still like these things, make-up and clothes were never the actual issue for any of us, they were secondary issues. The real main issue is your body and how you feel about it, everything else is commonly something we dislike because of the connection we make with it being male or female and how it may make us appear a certain way to ourselves and others.
Good luck. And remember, your first appointment is for you and them to get a feel for one another and if you will be able to work together. If you are not comfortable or don't feel they understand or support you on the issues you'd like to work on move on to another therapist. Even though I had met my therapist several times before I made an appointment with her (social gatherings for the GLBT community and things like that were she spoke as a guest) she still made it very clear that our first appointment was to decide if I liked her and wanted to see her as a therapist at all.
