Usually, housing offices won't require an in-person interview until your name reaches the top of the waiting list. However, some offices may require an interview immediately upon submitting your application, or schedule an interview at a later date.
Housing office policies also differ on who is required to attend the interview. Some require all household members to be present, while others only ask for either all adult (18+) household members, or just the applicant to attend the interview.
If you apply to a waiting list in an area outside of your current location, you should plan to travel to that location at some point before receiving rental assistance.