I don't think it's unfair.
Actually, the only way it would be unfair is if this was something important to her. If it's not something important to her, then there's nothing unfair about it. And if having the guy's first kiss is important to her, then she can reject me and find someone else!
But most girl's who have kissed before having done so A LOT. I've kissed a girl before, but not a lot at all. I never had a long relationship before.
Also... I won't kiss a girl unless I believe we are strongly heading in the direction of marriage. Many girl's kiss guy's that aren't even that interested in them! At least I have the practice where I won't kiss a girl unless I intend on marrying her later