It's really a toss-up. Sometimes the middle of the night is okay, but most of the time it's not too good. There's no real rhyme or reason to any of this, but what I have found is that most of the time mid to late afternoon (3-6pm) is optimal. That would be approximately 9pm-12 midnight your time?
Also, mid mornings (9-11am) seems to be good for me. When I get the chance to submit at those times, that is. Lol!
But in all reality, there isn't any set times that your memes will get optimal views and the fact that you have no idea when exactly your memes will be featured. If I submit a meme at 7am or 12 noon, my time, I seem to get a few more views.
It also depends on where your meme features on the "latest" section. Original memes (using templates you get off Google search or templates you create) take a lot longer to feature and therefore will probably feature on pages 3-10 on the "latest," where templates that are already on the site will usually feature within 2-3 hours and have a better chance at featuring on the first few pages on "latest."