Before somebody else comes along and says it, let me say that the number of hits shouldn't be the objective. Now that I've been the first to say it, let me also be the first to say that I don't believe it--we post because we want our work to be seen. Still, My work typically doesn't draw a lot of hits, unless I create provocative thumbnails. And in the end, the number of hits truly feels like a shallow pleasure...what satisfies most is the instant message I get from somebody who likes my work. I also find it gratifying to notice that somebody has surfed the rest of my gallery (even my homepage) as a result of having liked my newest image. But to answer your question...early evening PST seems to generally be best. Weekends especially. And a naked boob in the thumbnail works wonders. Good luck.