Baby sign language is awesome. If you've got a little bundle of joy, I highly recommend you incorporate them into your daily communication with him/her as soon as possible. This website has all kinds of resources, and you can find lots of other information and testimonies online.
Don't be like me. One of my biggest regrets in motherhood so far is not using more baby sign language, and not starting sooner. I've been using the signs for "more" and "all done" halfway consistently since she was about 7-months-old, but that's about it.
I wasn't sure it would take, but this week Penny surprised me when she signed that she wanted "more" ice cream after her little bowl was empty. Of course it would be ice cream that earned the first use of a baby sign, she's definitely my daughter.
Just yesterday morning she signed to me that she was "all done" with breakfast and ready to get down from her eat seat. She's been using "all done" ever since. It's so glorious for her to be able to tell me that she's done instead of starting to kick or fuss or climb out of her seat by herself.
This week she's also been waving "hi" like it's her job and offering high-fives. SUCH a fun age.
I think the most important thing during this time when Penny is really communicating with us is that we pay attention to her. This might seem like it should go without saying... but baby communication is very subtle (until it turns into a tantrum) and it can be so easy to miss the cues and miss teaching opportunities. I'm really trying to tune out distractions when I am with her, so I can deeply know her language and she can deeply trust that I am listening.