Well, this is typically when I'm online, except it is now 3:00 AM (EDT) local time and I live on the east coast of the USA. My target audience is sound asleep right now. If I were to make a meme right now, I would wait about 6 hours and AND THEN SUBMIT IT.
In other words: I can't control how long it takes between the time of submission and when it's featured, but I CAN control WHEN imgflip first sees it!