Yeah...
If I were you I would take some time getting to know him (like a week or so) and just see how he seems to act. He'll be at least 18, so he has knowledge of orientation and whatnot, so gay people wont be new to him, I'm sure.
However, you'll be able to tell if he's nice and whatnot, and by his actions and personality, you can easily judge around his point of view in some things. So if he seems like a pretty chill dude, just let him know face to face. NOT awkwardly. Please. Don't be like, "Hey, so I have something to tell you, uhm. Please don't hate me. Uhm. i'm really nervous." .... No. just a simple, "Hey, by the way, not that it's a big deal, but I'm gay. " -- wait for any reaction -- "That doesn't bother ya or anything right? I swear I wont rape you in your sleep, man!" etc. etc. Then make sure to talk about any housing rules and guest rules. So he knows what's coming up and you know what's coming. If you're both going to have significant others invited or whatever.
I really don't like that whole, "Just tell him and if he doesn't like it, f*ck it, do your thing anyway. " thing because that's just not the way to go about things, in my opinion- it's disrespectful.
And I wouldn't lead him up to it by having gay flicks on or posters of Brent Everett on your wall, either, because that's pushing his buttons, disrespectful, and going to make him feel uncomfortable and higher chances of leaning towards awkward/ a negative start to your relationship.
Just for giggles, here's my coming out story to my ex-roomy:
Last August, we were both 19 (now 20):
He went to a military training high school and comes from very conservative parents. He has a knife uder his bed, so I was actually... uhm.. a bit worried.
He's about 6'1'' a bit muscular, and luckily a bear at heart.
During the first two weeks of school, we talked about simple things in life, when he mentioned girls, I would just turn the tables to let him do most the talking in that category, and so forth. during the first week, he wore a neon green shirt and I told him, "man, you look pretty damn gay" and his reaction was just laughter (this was a little clue that he doesn't take the word "gay" into anything serious, and just a word. I was looking for something negative, like, "dude, that's not cool". or something along the lines of that). He was pretty friendly with his friends, too. That straight wanna be gay slap in the butts, "good game!" and what not. Which shows comfort with his sexuality and possibly a sign of not minding other's people business, aka, not caring who's gay and who's not.
Then during the 2nd week, I invited him to go out dancing with some friends and I and he said okayyy. I was going with 5 gay guys, 2 gay girls, and 1 straight girl.
We got to my firend's apartment to pre-game and when we were walking up the stairs, I told him, "by the wayyyyyyy, just to fill you in some quick details, I'm gay and everyone you're about to meet is gay except for one straight girl... good luck, and please don't slice me with your knife."
His reaction: "Whaat?! And you tell me now?!"
Me: "Yeahhh, sorry about the bluntness, better now than never, rightttt? You don't have any problems, right?"
Him: "Hahahaha, no I don't care, I had a feeling"
And we went on on our merry way.
Then later when we got back from dancing to our dorm we talked about further details and whatnot.
Hope that helps. :|
Just remember that being gay is NOT a big deal, so try not to make it one. Or things get fuzzy. :/
Good luck!