As you know you have
Starting to prepare your children
for a new family addition should be natural.
You can guide them through, why the mommy's belly is getting bigger, when you know the gender, you can tell them who is coming to joint them. Develop a role playing of big brothers and sisters and how they will take care of the baby, helping to feed and change the diapers, what they can do to help a mommy with a newbor.