Create a slow pace speaking environment at home. This means everybody must speak with longer pauses and pause more often. Wait a few seconds more before responding to his question. And give him a few more seconds to begin his sentence, and next sentence and so on. Be aware that secondary behaviors can happen. Such as frowning, blinking hard, eyebrow raising, or looking elsewhere or excessive use of filler words or trying a new accent. Do not finish his sentences for him unless he explicitly asked you to do that.