I take personal offense to the tone of some of the comments made here. I know the intention of them but as a trans woman who is attracted to men, I don't like the wording. I bring this up in hopes that it reminds people that there are more than just part time crossdressers here.
Natalie,
Be honest with him about your expectations. Avoid sex on the first date unless it is mutually agreed upon prior to the date. Be safe and enjoy yourself. I suggest brining up if he is ok with your presenting as female on your date unless you have already mentioned that to him. You said he is aware of your crossdressing but I don't know if you meant that you will be feminine on your date.
Most importantly, he is taking you out on a date so let him be the one in charge of giving you a good time.