How long was the main character from The Walking Dead in a coma?

I've been watching the new show The Walking Dead. In the first episode he woke up from a coma after being shot and after the zombie outbreak happened. So how long was he in a coma for? How long after he fell into the coma did the zombie outbreak happen? I don't think it said in the show but maybe it did in the comics since it is based off the comic series.