You cannot petition your daughter until you become a permanent resident, and you do not become a permanent resident until you enter the US with your immigrant visa. Assuming your daughter really aged out (with the CSPA calculation), there is nothing you can do at the interview, because you cannot petition her because you are not a permanent resident yet.When you enter the US with your immigrant visa, you immediately become a US permanent resident, and you can immediately can file an I-130 petition for your unmarried daughter, with your immigrant visa stamped upon entry as proof of your permanent residence. She does not u201cautomaticallyu201d have a petition, you must petition her yourself. Note that an unmarried over-21 child of a permanent resident is in the F2B category, which has a wait of around 7 years, and this is 7 years counting from when the petition you file for her is filed (after you enter the US), not the petition that you immigrated on.