回複：謝謝回答，處理I-290B需要時間，我可以馬上在申請i-824嗎？

you should wait until you receive the denial notice before filing I-290, because otherwise you don't know the grounds of denial and cannot make meaningful arguments. But in any case, the I-290 shall not be filed more than 30 days from the date of denial.

Your child's age is not an issue. He or she is protected by Child Status Protection Act.