When you post a question as a Q&A, it appears in unedited and unanswered form. When it gets answered depends on a specific model of how editors are organized.
Most editors working at eNotes are not employees, but freelancers who are paid per answer. When editors log in, they can look at unanswered questions and choose which questions to answer. Thus how long it takes to get a question answered depends on whether editors with expertise in a specific area happen to log in and choose to answer the question. Thus there is no fixed wait time -- although premium users are more likely to be answered quickly (editors are paid more for premium answers).
Since the editors are paid per question, a straightforward question that requires only minimal editing is more likely to be answered quickly.