I tend to have days when I simply make more memes than can be submitted in one day. So, for example, right now there are probably 10-15 memes created and ready to go. But with a daily limit of 2 to the 'fun' stream, that's several days worth. Of course there are lots of days when I simply do not have the time or creativity to create any for that exact day.
I usually avoid making them ahead of time, because sometimes it seems like the age of the meme is counted in latest whether it's submitted or not, and the meme winds up buried on page 70 or something. But hey, if it works for you, awesome :)