A.P.
If he is behind in speech, go see a Speech Language Pathologist to see if is is really behind to the point of needing help. Little people do not communicate well without language, and teeth are the most empowering force they have! If he needs help with language, his behavior will continue. If it's really speech, sign language will only delay the inevitable need for talking, so I'd suggest a screening.
As for time outs, they aren't intended for a discipline measure, but instead to help a child regain control. Timeouts for a baby that age won't work, unless the time out is in your arms. "No biting. That hurts mama. Show mama love" then hug him. Make him "do" what is kind if he acts aggressively. Teaching him to fix it will go a lot farther than just punishing him. Good luck figuring out your plan...hopefully he won't bite again!