J.S.
We did it and it's awesome. My husband always says he doesn't know what we would do if we didn't have it, it really helps them show you what they need and eliminates a lot (but not all) frustration. We just got a small pocket book called, Baby Sign Language Basics by Monta Briant (Target I think). We also look up new signs at www.aslpro.com they have videos. Our toddler loves looking them up with us and learning new ones. I highly recommend it. We started around 4 months but don't get frustrated, their motor capabilities aren't there until later. I think he was around 7 or 8 months when we started noticing his signs. Also, you have to watch for it, lots of times they aren't exactly like the actual signs and can be easy to miss. Feel free to ask me any questions!