Parents have a unique opportunity to teach language in natural situations. As a parent, you are the constant in your child's life. Schools, therapists, and teachers may change, but you are always there. If you understand your child's device and effective implementation strategies, you can help train new members of the team.
You can't teach your child a skill you don't have. Learn your child's device. Know how to communicate with it and know how to program it. Practice, practice, practice!
Kids with language delays have difficulty learning concepts by being told what they mean. They need to see it and experience it! To develop expressive language, you'll want your child to pair a consistent motor movement with hearing the word and seeing something happen.
Initially, give them an opportunity to use words and see a response without a right or wrong answer. Provide opportunities for errorless learning. Ask open ended questions. Don't focus on labeling items or testing their knowledge.
"Which color do you want to wear?" or "What color should I wear?"
Teach core words in a variety of activities throughout the day.
If a child "says" a word you don't think he meant to say, respond to it anyway. This provides an opportunity to teach a new word.
Encourage them to communicate for a variety of reasons, not just to request an item or activity. Allow them to practice their language with greetings, rejection, commenting, directing, describing, etc.
Briefly encourage device use during activities while they are meaningful and enjoyable but quit while it's going well. There is a danger in pushing too hard and too fast in that the child will see the device as something that makes his life harder.
Follow your child's passions or interests, you can expand your child's vocabulary around them.
Accept all forms of communication: gestures, facial expressions, intelligible verbalizations. If you understand what the child is saying, don't make him "say it on your device." If you don't understand, "Can you tell me this way?"
Model the language at your child's level of communicating. If he uses one or two word combinations, don't model complete sentences. Allow siblings to use the device.