It's too young to tell right now. Wait about a month and if the comb starts combing out and widening, then it'll more than likely be a roo. But I'll throw a guess out there and say it's a boy! Good luck!
Hard to tell this young, but because they have large single combs watch for pink color on that comb...the pullet's should stay yellowish for a long time, whereas the male's will get color much earlier.