Topic: F4 Visa Interview Questions - Mumbai Consulate

I have my visa F4 visa interview scheduled at the Mumbai Consulate on 05/28/2024, Can someone please any interview question that might be asked for the F4 visa category

Topic: When should I pay the AOS and IV fees

I belong to the F4 category visa. I have received the NVC case creation email on February 8,2021 with nvc case number and invoice id. Should i pay the fees within 1 year from the date that i received the email(i.e. February 8,2022). Or will NVC contact me again to start paying the fees?