You've got PLENTY of time to train, which is great. I ran my first 1/2 this past fall, and trained seriously for about 9 weeks, which was fine for me (I had been running a lot before the training, but not running geared toward the 1/2 distance). There are a number of great training plans out there - pick one and stick with it. Also, listen to your body - if you are due for a long run, but you feel especially tired or sore, take a rest day instead (and don't feel guilty about it!). Training smart to prevent injury is key, and mix in a lot of varied running such as speedword, tempo runs, hills, plus the long run - that will give you a great mix of endurance and speed to give you the strength you'll need for the 1/2.
I LOVE this distance - had a great race, and can't wait to do another. It's a perfect distance for me - I hope that you enjoy it as well!
One more thing - if you don't run with either a friend or a running group already, I'd highly recommend finding one. It helps out SO much when you are training with someone else, especially when you are heading out for a 12/13/14 mile run!
m.