They usually review all articles on a certain moment. When I submit 3 articles (where the last one was submitted at max 48 hours later), I usually receive 3 notifications (of approval and/or denial) within the same hour.
Sometimes they'll get accepted within 24 hours, sometimes 3 days, and sometimes it may take longer than a week. But you will receive a notification about the article you've sent in. Just gotta be patient. Meanwhile, keep writing for more gems.