Don't worry about timing of uploads at DP or anywhere else.  If the only way your pictures will sell is if you are at the top of the "Latest Uploads" at the most visited time, then there is something wrong with what you're uploading.  It means that your strategy is to upload "more of the same." 

Instead, focus those energies on planning and creating more unique stuff -- in-demand subject matters that aren't already done to death, a unique style that's all your own -- and buyers will find them.  That approach will lead to much larger sales than playing the guessing game of what's the best moment to upload stuff that would not otherwise stand out.

I upload when it works well for my schedule.  I don't give a second thought to whether it's good timing for reviews and ultimate placement on the sites.  My sales have done just fine.