I have three stepchildren who call me by my first name. How can I ensure that my biological child will call me "Mommy" and not call me by my first name like his stepsiblings?
Your son may figure this out on his own--after all, children learn to call their mothers "Mommy," even though Dad calls the mother by her first name or "Dear" or "Sweetheart." You might wait to see what happens, or you can introduce the term "Mommy" when he first begins to say single words, like "No" or "Bye-bye." Make a brief little game out of echoing his words back to him, saying playfully "No, no, Mommy!" or "Bye-bye, Mommy!" You can play peek-a-boo with your son, saying, "Here's the Mommy. Here's the little boy!" The capacity of small children to catch on to names and words like "you" or "me" and to use them properly is one of the mysterious miracles of development!