This regime officially came into force a year ago, but has become mandatory from yesterday for US tourist Visa. Most passengers will receive the approval of Form in minutes, but British Airways and American Airlines are advising all to have at least 72 hours in advance. The director of customer service British Airways, Sill Maize Said: It only takes 15 minutes to complete the form THIS, And the vast majority of applicants receive approval for the trip in a matter of minutes but may take up to 72 hours. Under the new regulations, we are not able to accept passengers bound for United States if they have received approval through the form THIS or if you do not have a visa or Green Card.