One mother told me she had a similar situation. One day she had mixed the contents of the baby s bottle and was about to give it to the child when the phone rang. After a few moments she looked around and her baby was reaching up and signing milk. After the mother responded, the baby began using more signs. That interaction ignited their communcation.
Children especially love making animal signs as books are read.
Let the baby discover and gain the empowerment that comes with discovery.