Your kid doesn’t need to be with you at the time of your oath. After you become the USC, your child will automatically become the USC when he is a GC holder living with you. Lets say you send your kid to Nepal at this time. Even if you bring your child to the US several months after you become the USC, your child will become a USC when he comes back and you can apply for child’s passport directly at that time. No need to do anything with USCIS unless you want to apply for child’s certificate of citizenship which is optional.