Asylum Offices around the country have become very busy. Oldest and newest cases, cases that were previously before the Immigration Court, and sometimes seemingly random cases are being scheduled for interviews. Often times, there is little advanced notice prior to the interview date. This means that applicants do not always have enough time to gather and submit their evidence, which is usually due at least a week before the interview.
Since it is not possible to know when you might be scheduled for an interview, or how much advanced notice you will have before the interview, the best approach is to gather your evidence now, so you are ready to go when the time comes.