If this is just your first time playing, then maybe not. Though if you have played before, OOT is easily beatable before SS comes out. I'm currently playing through OOT's Master Quest on the 3DS.
Let's say you do a dungeon a day, at that rate it will take you ten days to complete the game excluding side stuff. However, if you 100%, it will probably take you a few extra days.
I just finished an OoT playthrough on Wii VC a couple weeks ago.
If this is yout first playthrough, I strongly suggest you take your time however. You have about a month, there's no rush.
If you can do the dungeons without needing to quit in the midsts of one and have more than 10 hours of free time definitly. I just started my first glicht run and I am wowed on the rate of my compleation.
You definitely should be able to beat OoT before SS comes out; you have a little less than a month!
A speedrun doesn't take that long, so if you're just looking to go from Opening Cinematic to Sword Cinematic (endgame), you shouldn't have any trouble at all.
I'm actually doing this, too. I'm in the Forest Temple. That's my favorite dungeon, in fact... I love the music, it's so mystical and unique.
Actually, I beat the Forest Temple and entered the Fire Temple, but then my game was interrupted and I forgot to save. So I have to start over the temples... Of course I can beat the rest of OoT in 18 days
Started Saturday, ended yesterday, 100%, final time 7:42:17.92. 100% (as defined here) speed-run record is 6:35:??.??. Obviously, I speed-ran OoT. Not too bad for my first speed-run of the game, but I expected to be a bit faster. Oh well, as with my ALttP speed runs, I still have a bit of work to do.