I've tried to submit "Popular Memes" early in the morning, between 5am-8am seems to work good. I've submitted them earlier but sometimes they'll feature at 5am and they miss the morning rush, too early, but that's not always the case. Socrates told me for "Custom Templates" submit them between 11am-Noon, 12:30pm latest. That's has worked well. I've submitted memes at ever hour in the day, it's really a "Feel" type of thing. You know, if you're here every day and get the flow that goes on, you'll be able to call it, but the times I gave work well. If you've have a meme that's hot, people will Upvote regardless of when you submitted it, have no expectations, submit it and check every so often, work on the next! Good luck and happy meming! :)