Yes, there are guys out there who would wait. I’d bring it up within the first few dates.
A good partner will respect the wishes of his SO, even before they exchange vows. However, as the voice of experience, do the both of you a favor and set VERY clear boundaries. What exactly is off the table until marriage? Strictly penetrative sex? No masturbating each other? No oral or anal play? Let him know where you stand as far as the most common sexual acts, especially ones outside of just PiV. If you are open to things like oral or mutual masturbation, that will be important to note.
As others have mentioned before, when it comes to sexual desires, explain why. In my husband’s case, it was very simple; he was raised in a very conservative household and he was somewhat religious. Knowing that why is critical. If you two may have conflicting ideals then it is better that they come out someplace outside of the bedroom.
Have this conversation soon, and be firm, but don’t treat it as a heavy topic. Be honest and gentle about it. If this guy is worth it at all, he’ll listen. 🙂
A final quick encouragement: Don’t be afraid to explore your own sexuality in the meantime. Touch yourself from head to toe and every bare spot in between. Look at yourself naked in the mirror and practice self-appreciation. Masturbate, for goodness sake! 😛 When the time comes, it will help you be more confident and knowledgeable. Good sex very rarely just happens, it takes time and effort, so start by learning what touches and such make you tick.
Even if you disregard that and want to test your partner, waiting until marriage is risky! Choose a couple of months (or at the very very worst, engagement). Waiting until marriage will likely result in realizing you’re sexually incompatible way too late, thus causing a divorce when it doesn’t work out. Not to mention, you’d be starting your marriage with a big fat lie, him finding that out will also cause resentment or divorce.